LIBRARY 


UNIVERSITY  OF  CALIFORNIA, 


Clasi 


The  D.  Van  Nostr and  Company 

intend  this  book  to  be  sold  to  the  Public 
at  the  advertised  price,  and  supply  it  to 
the  Trade  on  terms  which, will  not  allow 
of  reduction. 


WATER    SOFTENING    AND 
TREATMENT 


WATER  SOFTENING 
AND     TREATMENT 

CONDENSING      PLANT,     FEED     PUMPS 

AND   HEATERS  FOR  STEAM  USERS 

AND   MANUFACTURERS 


By 
WILLIAM   H.  BOOTH 

« I 

STEAM    ENGINEER,  ARTESIAN  ENGINEER  AND  HYDROGEOLOGIST  ;  MEMBER  OF  THE  AMERICAN 
SOCIETY  OF  CIVIL  ENGINEERS;  FORMERLY  HON.  SEC.  ENGINEERING  ASSOCIATION  OF  NEW 
SOUTH  WALES;    OF  THE    NEW  SOUTH  WALES  GOVERNMENT  RAILWAY  DEPART- 
MENT ;    LATE    OF    THE    MANCHESTER    STEAM    USERS  ASSOCIATION  ;    LATE  OF 
THE      BRITISH       ELECTRIC        TRACTION       COMPANY  ;       AUTHOR      OF 

"LIQUID  FUEL  AND  ITS  COMBUSTION,"  "SMOKE  PREVENTION 

AND    FUEL    ECONOMY,"    "  STEAM    PIPES    THEIR 
DESIGN     AND     CONSTRUCTION  " 


NEW   YORK 
D.   VAN   NOSTRAND   COMPANY 

23  MURRAY  AND  27  WARREN  STS. 
1906 


SENERAL 


BUTLER  &  TANNER, 

THE  SELWOOD  PRINTING  WORKS, 

FROME,  AND  LONDON. 


PREFACE 

r  I  ^HE  treatment  of  water  for  steam-boiler  and  manu- 
facturing purposes  is  a  question  of  prime  importance 
to  the  steam  user,  who  understands  by  treatment  something 
that  will  reduce  the  amount  of  hard  scale  deposited  in  his 
boiler  or  fabrics.  Incidentally,  such  reduction  benefits  his 
pocket  by  reason  of  the  better  efficiency  of  the  boiler-heating 
surface  ;  less  obviously  but  as  certainly  there  accrues  to 
him  a  saving,  because  his  boilers  are  less  strained  ;  labour 
is  economized  upon  cleaning  and  the  number  of  boilers  at 
work  and  spare  may  be  less  for  a  given  duty.  No  apology, 
therefore,  need  be  put  forward  in  attempting  to  lay  before 
steam  users  some  of  the  chief  facts  connected  with  the 
softening  of  water.  Equally  important  is  the  subject  to 
certain  manufacturers,  notably  dyers,  one  of  whom  informed 
the  author  that  foreign  competition  in  dyeing  had  no  terrors 
for  him.  He  could  obtain  for  his  dyed  wools  in  delicate 
shades  sixpence  per  pound  more  than  other  dyers,  for  he 
employed  a  water-softening  process,  whereas  his  neighbours 
were  content  to  use  untreated  water. 

There  are  limits  to  the  powers  of  the  water-softening 
chemist,  and  it  is  well  these  limits  should  be  recognized  in 
order  to  prevent  disappointment ;  but  there  are  few  cases 
which  cannot  be  taken  in  hand  and  some  improvement 
secured.  No  attempt  is  made  to  enter  too  deeply  into  finer 
points  of  chemistry.  Water  softening  and  general  treat- 
ment for  the  steam  user  must  of  necessity  be  kept  within  the 
bounds  of  the  more  simple  reactions  and  the  commercial 
reagents. 


PREFACE 

In  laundries  chemicals  are  added  in  the  wash-tub  for  the 
purpose  of  softening  water  and  saving  soap.  London  water, 
say  Messrs.  Mather  &  Platt,  will  destroy  20  Ib.  of  soap 
per  1,000  gallons,  at  a  cost  of  3s.  4d.,  whereas  the  water 
could  be  properly  softened  before  use  for  Id.  per  1,000 
gallons. 

By  using  softening  chemicals  in  the  wash-tub  the  soap 
is  saved,  but  the  lime  salts  are  deposited  in  the  texture  of 
the  things  washed,  and  these  acquire  a  yellow  tinge.  As 
well  as  in  steam  boilers,  hard  water  is  harmful  and  costly 
in  laundries,  tanneries,  dye  works  and  paper  mills,  etc.,  for 
iron,  which  exists  in  many  waters,  is  removed  in  the  process 
of  softening. 

In  dye  works  the  most  delicate  colours  cannot  be  obtained 
except  with  soft  water,  and  in  the  tanyard  the  presence  of 
lime  carbonate  in  the  hides  destroys  tannin  by  converting 
it  into  lime  tannate,  and  this  is  not  only  a  loss  of  tannin 
but  detracts  from  the  quality  of  the  leather,  which  is 
hardened  and  rendered  harsh  in  feeling  through  the  choking 
of  its  substance  with  mineral  matter. 

In  preparing  this  volume  the  Author  has  drawn  on  many 
sources  to  supplement  his  own  experience,  and  is  indebted 
to  various  firms  for  kindly  supplying  information  of  their 
particular  apparatus,  which  have  been  selected,  as  explained 
in  Chapter  VIII.,  purely  as  types  of  construction  and  not 
because  such  apparatus  is  in  his  opinion  better  or  worse 
than  others  named  or  unnamed. 

The  complaints  as  to  the  destruction  of  fabrics  in  laundries 
by  the  use  of  chemicals  arise  probably  as  the  result  of  using 
chemicals  in  dry  form  thrown  directly  into  the  washing  vats. 

The  same  chemicals,  properly  employed  in  correct  quantity 
would  do  no  harm,  but  rather  good.  Where  softeners  are 
used  in  the  washing  vessels  themselves,  even  in  correct 
quantity,  the  goods  are  exposed  to  the  lime  salts,  which  are 

vi 


PREFACE 

thrown  out  of  solution.  It  is  thus  in  every  way  best  to 
soften  water  as  a  preliminary  operation  and  to  remove  the 
separated  lime  salts  by  deposit  and  filtration. 

The  second  part  of  the  book  deals  with  Condensing  Plant, 
Feed  Pumps  and  Heaters,  and  Water  Coolers,  and  appears 
naturally  to  ally  itself  with  the  subject  of  water  softening. 
The  examples  illustrative  of  these  sections  are  also  selected 
for  the  same  reasons  as  those  in  the  first  portion  of  the  book. 

The  Author  has  endeavoured  to  make  clear  the  important 
bearing  which  the  laws  of  mixed  vapours  have  upon  the 
subject  of  condensing,  and  hopes  that  thereby  the  folly  of 
overrunning  of  air  pumps  may  be  more  clearly  perceived. 
Not  only  upon  condensers,  but  also  upon  air-pump  design, 
these  laws  have  their  bearing.  Rankine  very  clearly  stated 
the  law,  and  was  more  than  usually  particular  in  illustrating 
it  by  plain  figures.  Yet  the  law  has  been  little  grasped. 
Indeed,  the  Author  has  been  induced  himself  to  emphasize 
the  point  by  Mr.  George  Higgins,  M.Inst.C.E.,  of  Melbourne, 
who  pointed  out  where  he,  vthe  Author,  had  himself 
neglected  to  give  sufficient  consideration  to  the  law. 

The  provision  of  condensing  plant  has  often  been  very 
fortuitous  in  the  past,  especially  in  electrical  stations,  which 
have  been  often  patched  up  in  a  very  haphazard  manner. 

Perhaps  no  detail  has  been  worse  neglected  than  the  feed 
pump.  It  is  to  be  hoped  that  the  future  will  see  a  full 
return  to  older  practice,  which  was  based  on  slow,  easily- 
worked  substantial  pumps,  which  did  not  strive  to  make 
their  presence  known  by  clouds  of  steam  and  a  perennial 
water  puddle. 

If  the  steam  engine  is  to  continue  to  hold  its  own  against 
newer  heat  motors  there  must  be  better  and  more  scientific 
practice,  based  on  a  recognition  of  those  factors  on  which 
permanence  and  durability  depend.  There  has  been  a  great 
departure  along  toy  lines,  and  much  attempt  to  hold  that 

vii 


PREFACE 

things  could  be  done  that  were  opposed  to  known  laws  and 
practical  experience.  The  result  as  regards  electrical  ex- 
perience has  been  millions  of  tons  of  coal  wasted,  and  in 
nothing  perhaps  worse  than  in  ill-considered  condensers  and 
feed-plant  apparatus. 

The  Author's  thanks  are  due  to  various  firms  for  informa- 
tion of  their  respective  apparatus. 

In  order  to  render  the  subject  more  complete,  sections  on 
Feed-heating  and  Water-cooling  have  been  added  to  deal 
with  these  essentials,  which  require  quite  as  much  care,  and 
judgment  in  the  selection  of  the  proper  apparatus  for  each 
case  as  do  the  other  matters  dealt  with. 

As  far  as  possible  the  basis  of  design  and  calculation  has 
been  made  the  British  Thermal  Unit,  for  by  its  use  the 
elements  of  design  all  fall  naturally  together,  and  the  hap- 
hazard system  of  basing  design  on  a  horse-power  basis  is 
altogether  too  foolish  to  be  seriously  entertained. 

WM.  H.  BOOTH. 

25,  QUEEN  ANNE'S  GATE, 
WESTMINSTER. 


vni 


CONTENTS 

SECTION  I 

THE   TREATMENT  OF  WATER  BY  SOFTENING,    OIL 
SEPARATION  AND  FILTRATION 

PAGE 

CHAPTER  I 

NATURAL  WATERS — SCALE — CLEANING  BOILERS — BENEFITS  OF 
PURE  WATER — GENERAL  LINES  OF  PURIFICATION — COOL- 
ING BOILERS — SOAP  WASTE — COSTS.  ....  3 

CHAPTER  II 

WATER  :  ITS  SOURCES  AND  IMPURITIES — NATURAL  HARDENING 
OF  WATER — GEOLOGY — NATURALLY  SOFT  WATER — RIVER 
WATER — PUBLIC  WATER  SUPPLIES — BORINGS — CHOICE  OF 
SITES  FOR  WELLS  .  .  „  .  ^  .  .  7 

CHAPTER  III 

THE  SALTS  CONTAINED  IN  WATER — LIME  AND  MAGNESIA  CAR- 
BONATES, SULPHATES,  ETC. — VARIOUS  OTHER  SALTS — 
CLARK'S  PROCESS  .  ,  «  .  .  .  .13 

CHAPTER  IV 

THE  REACTIONS  OF  SALTS  IN  SOLUTION — CHEMICAL  FORMULAE 
—FLOURY  DEPOSIT — EFFECTS  OF  HEAT — GREASE — MAG- 
NESIA EFFECTS — MILK  OF  LIME — LIME  WATER — SODA, 
SODA  ASH,  BUXTON  OR  FAT  LIME — BARIUM  ALUMINATE  .  19 

CHAPTER  V 

THE  LESS  USUAL  REAGENTS — SILICATE  OF  SODA — OXALATE 
OF  SODA — ALUM — ALUMINO  FERRIC — HEAT — BARIUM 
CARBONATE,  BARIUM  OXIDE,  ETC.  •  .  .  .  .27 

CHAPTER  VI 

SCALE  AND  ITS  EFFECTS — STROMEYER'S  TABLE  OF  HEAT  DIS- 
TRIBUTION   IN    BOILERS — GREASE — ORGANIC    MATTER — 
EFFECT    OF    SCALE — PLATES    OF    BOILER    UNDERNEATH 
SCALE — COLLECTION  OF  SCALE     ...          .          .          .32 

CHAPTER  VII 

WATER  ANALYSIS — STANDARD  SOAP  SOLUTION — STANDARD 
HARD  WATER — FRENCH  SOAP  SOLUTION — APPARATUS  FOR 
ANALYSIS — SOLUBILITY  OF  GASES  AND  SALTS  IN  WATER 
— BOILING-POINTS  OF  SALT  SOLUTIONS  ...  36 

CHAPTER  VIII 

APPARATUS  IN  COMMERCIAL  USE — SETTLING  TANKS — CON- 
TINUOUS PROCESS — APPLICATION  OF  REAGENTS — PRO- 
PORTIONING REAGENTS — COST  OF  SOFTENING  .  .  44 

ix 


CONTENTS 

CHAPTER  IX  PAGE 

EXAMPLES  OF  APPARATUS — THE  ARCHBUTT-DEELEY — CRITON, 
DOULTON,  GUTTMANN,  BAKER,  REISERT,  BRUNN-LOWENER, 
DESRTJMEATJX,  STANHOPE,  WOLLASTON,  CARROD,  PATERSON 
— COST  OF  SOFTENING — SIZE  OF  APPARATUS — WORKING  .  48 

CHAPTER  X 
DETARTARIZERS — DELHOTEL,      GRANDDEMANGE,     CHEVALET- 

BOBY — WEIR  FEED  HEATER — PATERSON  FEED  HEATER        83 

CHAPTER  XI 

FILTERS — FILTERING  MEDIA — SAND  FILTRATION — SETTLING 
POND — RETAINING  WALLS — TANK  CONSTRUCTION — CAST- 
IRON  TANKS — QUALITY  OF  SAND — RAPID  FILTERS — THE 
REISERT  FILTER  .......  88 

CHAPTER  XII 
BOILER  COMPOUNDS — FRENCH  PRACTICE — DISINCRUSTANTS — 

VARNISHES — CLEANING  A  BOILER — THE  USE  OF  ACIDS     .        96 

CHAPTER  XIII 

CORROSION — PRICES  OF  CHEMICALS — EFFECT  OF  ACID  WATER 
— GROOVING — GALVANIC  ACTION — DANGEROUS  FEED  SUP- 
PLIES— CORROSIVE  WATERS  .  .' ;  .  .  .102 

CHAPTER  XIV 

INCRUSTATION  OF  PIPES — ACTION  OF  SURFACE  WATERS — 
FERRUGINOUS  WATER — ANGUS  SMITH'S  COMPOUND — 
SOLVENT  ACTION  ON  LEAD  .  .  *  .  .  v .  107 

CHAPTER  XV 

OIL  SEPARATION — GREASE  EFFECTS — OIL  SEPARATORS — 
HOOPER'S  SEPARATOR — CHEMICAL  OIL  TREATMENT — CO- 
AGULATION OF  OIL — PATERSON'S  GREASE  SEPARATOR  .  109 

CHAPTER  XVI 
MECHANICAL  BOILER  CLEANERS — THE  HOTCHKISS  APPARATUS 

— ACTION  OF  MECHANICAL  CLEANERS    .          .          .          .119 

CHAPTER  XVII 
PURE   WATER — STANDARD   OF   PURITY — EFFECT   OF   COPPER 

SULPHATE — DRY  STEAM  AND  BREWING          .          .          *     121 

•  * 

APPENDIX  I.     REPORT  OF  DR.  ANGUS  SMITH  TO  THE  MAN- 
CHESTER   STEAM    USERS'    ASSOCIATION    ON 
SOFTENING  WATER     .          .          .          ...      123 

,,  II.     TABLE    IX. — THE    SOLUBILITY    OF    GASES    IN 

WATER  AND  ALCOHOL         .          .  ,140 

,,         III.     INFLUENCE    OF    SALTS    ON   BOILING-POINT   OF 
WATER — TABLE    X.  :     THE    SOLUBILITY    OF 
SALTS  AND  BOILING-POINTS         .          .          .142 
,,         IV.     WATER  AND  ITS  PROPERTIES — TABLE  XII. :  THE 
SOLUBILITY  OF  SALTS — SOLUBILITY  OF  LIME  AND  ITS  SALTS     144 


CONTENTS 

SECTION  II 

AIR  PUMPS,  CONDENSERS,  AND  CIRCULATING  PUMPS 
CHAPTER  XVIII  PAGE 

HEAT — SPECIFIC  HEAT — LATENT  HEAT — UNITS  OF  HEAT — 
UNIT  OF  WORK — THE  THERMAL  UNIT  AS  A  BASIS  FOR 
DESIGN — THE  BAROMETER 149 

CHAPTER  XIX 

CONDENSING  APPARATUS — MEAN  PRESSURES — VALUE  OF 
VACUUM — TABLE  XIII.  :  PROPERTIES  OF  Low  PRESSURE 
STEAM — LAW  OF  MIXED  VAPOURS — AIR-PUMP  ACTION — 
WATER  REQUIRED  FOR  CONDENSING — RATIO  TO  FEED 
WATER — CAPACITY  OF  CONDENSERS — VARIETIES  OF  CON- 
DENSERS— THE  JET  CONDENSER — THE  SURFACE  CON- 
DENSER— TURBULENT  FLOW  IN  TUBES — EJECTOR  CON- 
DENSER— ATMOSPHERIC  CONDENSER — CALCULATIONS — 
GENERAL  DESIGN — WORKING  OF  AIR  PUMPS — LOCATION 
OF  CONDENSING  PLANT — CIRCULATING  WATER — SILTING 
OF  PIPES — AIR- PUMP  DRIVING — EXHAUST  PIPES — COOL- 
ING SURFACE — BAROMETRIC  CONDENSER — JET  CONDENSER 
— COOLING  SURFACE — INCRUSTATION — ECONOMY  OF  CON- 
DENSING— SOLUBILITY  OF  GASES  IN  WATER  .  .  .154 

CHAPTER  XX 

EXAMPLES  OF  CONDENSERS — WORTHINGTON'S  BAROMETRIC 
HEAD — THE  WHEELER  CONDENSER — MORTON'S  EJECTOR 
CONDENSER,  BY  LEDWARD — SURFACE  CONDENSER — THE 
VERTICAL  CONDENSER  —  EVAPORATIVE  CONDENSER — 
COUNTER- CURRENT  CONDENSERS  :  JET,  SURFACE, 
BALCKE'S — BRACKETT'S — ATMOSPHERIC  VALVES  .  .  173 

CHAPTER  XXI 

AIR  PUMPS  :   PLAIN,  EDWARD'S — WORKING  OF  PUMPS — BARO- 
METRIC  EFFECT — THE     AIR-PUMP    BUCKET — GENERAL 
FORMS         .          .          .          .          .  '.         .         -      194 

CHAPTER  XXII 

TYPES  OF  Am  PUMPS  :  "  THE  EDWARDS,"  ELECTRICALLY- 
DRIVEN  PUMPS,  COMBINED  AIR  AND  CIRCULATING  PUMP, 
VERTICAL  AIR  PUMP,  EJECTORS,  DISPLACEMENT  PUMPS, 
THE  HORIZONTAL  AIR  PUMP,  TAIL-ROD  PUMPS,  STEAM- 
DRIVEN  PUMPS,  COMPOUND  AIR  PUMPS,  JET  AUGMENTOR, 
ROTATIVE  PUMP,  LOCATION  OF  CONDENSING  PLANT  .  .  201 

CHAPTER  XXIII 

CIRCULATING     PUMPS — DISPLACEMENT     TYPE — CENTRIFUGAL 

PUMP — COEFFICIENT    OF  CONTRACTION  OF  FLOW  .          .218 

xi 


CONTENTS 
SECTION  III 

FEED  HEATING— STAGE  HEATING 

CHAPTER  XXIV  PAGE 

FEED  HEATING — ECONOMIZERS — ECONOMY  TABLES — PURE 
WATER  ECONOMIZER — FULLY  HEATED  FEED  WATER — 
STAGE  HEATING — BOILER,  ETC.,  FOR  STAGE  HEATING — 
THE  NORMAND  EFFECT — WEIR  FEED  HEATER — SURFACE 
FEED  HEATERS — TRAY  FEED  HEATERS  ....  223 

CHAPTER  XXV 

PRACTICAL  APPLICATION  OF  STAGE  HEATING — THE  "  CRUSE  " 
APPARATUS — THE  COMBINED  FEED  HEATER,  BOILER  AND 
SUPERHEATER — STEAM  MANUFACTURING  244 


SECTION  IV 

WATER  COOLING 

CHAPTER  XXVI 

WATER  COOLING— HYGROMETRIC  PROPERTY  OF  AIR — CALCU- 
LATION OF  AIR  FOR  COOLING — COUNTER  CURRENTS — THE 
POND  —  EVAPORATION  —  ATMOSPHERIC  EVAPORATOR — 
TOWER  COOLERS — FAN  COOLERS — SPRAY  NOZZLES  .  .  255 

SECTION   V 
FEED  PUMPS— INJECTORS 
CHAPTER    XXVII 

FEED  PUMPS — EFFICIENCY — HEAD  AND  PRESSURE  OF  WATER 
— BAROMETRIC  PRESSURES — WEIR  PUMP — DIRECT- ACTING 
STEAM  PUMPS — DUPLEX  FEED  PUMP — FLYWHEEL 
PUMPS — "  FROMENTIN  "  FEEDER — THE  INJECTOR — THE 
EXHAUST  INJECTOR — VELOCITY  OF  FLOW  OF  STEAM — 
CAPACITY  AND  POWERS  ...  .  .  .271 

APPENDIX  V.  SOLUBILITY  OF  AIR  IN  WATER — TENSION  OF 
WATER  VAPOUR — EQUIVALENCE  OF  WATER 
AND  MERCURY  PRESSURES — STEAM  TEM- 
PERATURE AND  PRESSURES — FACTORS  OF 
EVAPORATION — ECONOMY  OF  FEED  HEAT- 
ING— SATURATED  STEAM  TABLE — USEFUL 
UNITS  AND  DEFINITIONS — ECONOMIZERS  .  289 

VI.     ELECTRICAL  OIL  SEPARATION    .  302 


XII 


LIST  OF  TABLES 


PAGE 

I  Heat  Distribution  in  Boilers     .          ..         V         .        32 

II  Loss  of  Heating  Power  due  to  Scale          .          .       34 

III  Solubility  of  Gases  and  Salts   .          .          .          .41 

IV  Boiling-points  of  Salt  Solutions          ...        43 
V  Cost  of  Softening  various  Waters      .                             53 

VI  Tank  Sizes  for  various  outputs.        .          .          .54 

VII  Dimensions  of  Doulton  Apparatus     .          ...        59 

VIII  „           „  Oil  Separators    .          .          .          .113 

IX  Solubility  of  Gases  in  Water  and  Alcohol           .      140 

X  „         „  Salts  and  Temperatures  of  Evapor- 
ation       ...          .          .          .142 

XI  Weight  of  Water  per  cubic  foot        .          .          .144 

XII  Solubility  of  Salts              .'....      145 

XIII  Properties  of  Low-pressure  Steam     .          .          .155 

XIV  Economy  of  Condensing     .          .          .          .          .171 
XV  Solubility  of  Gases  in  Water    .          .          .          .172 

XVI  Centrifugal  Pump  sizes     .          .      -   .          .          .205 

XVII  Capacity  of  Ejectors          .                     ;          .          .205 

XVIII  Saving  due  to  Feed-heating      ....      230 

XIX  „         „         „         „                                               .     231 

XX  Economizer   Performance.                     .          .          .      232 

XXI  „              Chamber  Spaces     .....      233 

XXII     Specific  Heat  of  Water 241 

XXIII  Expansion  of  Water         .          .          .          .          .242 

XXIV  Hygrometric  Property  of  Air    ....      256 

XXV  Output  of  Spray  Nozzles           .          .          .          .268 

XXVI  Head  and  Pressure  of  Water    .          .          .          .273 

XXVII  „         „         „             „„....     274 

XXVIII     Areas  of  Circles 275 

XXIX  Pump  Suction  at  various  Altitudes.          .          .     276 

xiii 


LIST    OF   TABLES 


PAGE 

280 
283 
288 
288 

289 


XXX     Capacity  of  Weir  Pumps 
XXXI     Capacity  of  Double  Ram  Pumps 
XXXII     Capacity  of  Exhaust  Injectors  . 

XXXIII  Height  of  Lift  for  Self-acting  Injectors     . 

XXXIV  Solubility  of  Air  in  Water  .  .        '  »   . 
XXXV     Tension     of    Water    Vapour    in    Millimetres    of 

Mercury 289 

XXXVI     Volume,  Specific  Gravity,  and  Tension  of  Water 

Vapour      \  ,        .          .          .          .          .          .     290 

XXXVII     Relative    Equivalence    of  Water    and    Mercury 

Columns       .  ....          .  .  .      291 

XXXVIII     Temperature   and   Pressure   of   Steam    for    each 

|-inch  of  Vacuum         .         .          .  .          .      292 

XXXIX     Factors  of  Evaporation 293 

XL  Percentage  of  Saving  due  to  Heated  Feed  .  294 
XLI  Temperature  Pressure  Table  of  Saturated  Steam  295 
XLII  Comparison  of  Regnault's  Experiments  with 

Rankine's  Equation  ...          .          ...     299 


xiv 


LIST    OF    ILLUSTRATIONS 

FIG.  PAGE 

1  The  Archbutt-Deeley  Apparatus  (Mather  &   Platt)       .        49 

2  The  Archbutt-Deeley  Apparatus  (Mather  &  Platt)        .       50 

3  The  Archbutt-Deeley  Apparatus  (Mather  &  Platt)        .        51 

4  The  Criton  Apparatus  (Pulsometer  Co.)  .          .56 

5  The  Doulton  Apparatus      ...          .        .  .          .          .        58 

6  The  Doulton  Apparatus      ......        58 

7  The  Guttmann  Apparatus  (B.  &  W.  Co.)       .          .          .        61 

8  The  Baker  Apparatus         .  .          .          .          .          .64 

9  The  Reisert  Apparatus  (Royle)  .....        66 

10  The  Brunn-Lowener  (Lassen  &  Hjort)  .          .          .        69 

11  The  Desrumeaux  ,          .          .          .          .          .71 

12  The  Desrumeaux       .          .          .          <  .          .        72 

13  The  Stanhope  ..         .          .          ...          .74 

14  The  Wollaston  .....          .         ..-         .76 

14a  The  Wollaston             ...          .          .          .          .          .77 

15  The  Carrod        .          .  .           .          ...        78 

16  The  Paterson     ......  '       .          .80 

16a  The  Paterson  (details)         .          .....        81 

17  The  Chevalet-Boby  Detartarizer  .          ...        .          .        84 

18  The  Chevalet-Boby  Detartarizer  (details)     .  .85 

19  The  Paterson  Feed-Water  Heater  and  Purifier     .          .        86 

20  The  Reservoir  Wall  Diagram      .          ..         .          .          .        92 

21  The  Reisert  Filter      .......        94 

22  Oil  Separator  (Holden  &  Brooke)        .          .        -  .          .      110 

OQ     "v 

~*    I  The  Baker  Grease  Separator       .          .          .          t          .111 

™  The  Baker  Grease  Separator      .                                         .      112 


24 
24a 


'  Illustrations  of  Coagulation       .          .  "         .  .  .114 

26  J 

27  The  Paterson  Grease  Separator  (section)     .  .  \      115 

28  The  Paterson  Grease  Separator  (elevation)  .  .      116 

29  The  Paterson  Grease  Separator  (plan)          .  .  .117 

30  The  Hotchkiss  Boiler  Cleaner      .           .          .  .  .119 

31  Primitive  Ideal  Barometric  Condenser          .  .  .169 

32  Jet  Condenser   .  .        ',.          .  .  .169 

33  Surface  Barometric  Condenser     .          .          *  .  .170 

34  Horizontal  Surface  Condenser      .          .          .  .  .170 

35  Worthington  Condenser  Head     .          .          .  .  .173 

36  Wheeler  Condenser     .....  .  .174 

37  Morton's  Ejector  Condenser  (Led  ward)         .  .  .      175 

38  Cross-  Section  of  Surface  Condenser  (Storey)  .  .      176 

39  Vertical  Condensers:    Yorkshire  Power  Station    .  .179 

40  Cross-Section  of  Horizontal  Condenser          .  .  .180 

41  Vertical  Single  Flow  Condenser  .          ,          .  .  .181 
41a  Vertical  Double  Flow  Condenser           .           .  .  .182 
416  Vertical  Single-Flow  Condenser  for  Muddy  Water  .      183 

42  Evaporative  Condenser        ..          .          .  .  .184 

42a  Evaporative  Condenser      .           .         '„          .  ,  ,185 

xv 


LIST   OF   ILLUSTRATIONS 


FIG.  PAGE 

43  Balcke's  Jet  Condenser       .           .          .          .  .  .187 

44  Brackett's  Concentric  Condenser           .      l    .  .  .  j      188 

45  Atmospheric  Valve  (Templer  &  Ranoe)        .  .  v     190 

46  Atmospheric  Valve  (T.  Walker)            .         \  .  ..191 

47  Atmospheric  Valve  (Spencer)       .                     .  .  .192 

48  Atmospheric  Valve  (Spencer)       .          .          .  .  .193 

49  Atmospheric  Valve  (details)         .           .          .  .  .      193 

50  Plain  Air  Pump          .....      ...  .194 

51  Edwards  Air  Pump  .......      196 

52  Edwards  Air  Pump  ......  .     201 

53  Electrically  Driven  Air  and  Circulating  Pump  .  .     203 

54  Double-Acting  Air  and  Circulating  Pump  .  .  203 

55  Vertical  Air  Pump     .          .           ..'.'.  .  .      204 

56  Ejector  Condenser      .          .          ...  .  ,     206 

57  Displacement  Air  Pump     .        '  .    '.       *                 '    ."  .     207 

58  Air  Pump  Diagrams.          .        -.          .          .  .  .     208 

59  Horizontal  Air  Pump           .          .  '        .          .  .  '    .     209 

60  High-Speed  Tail-Rod  Pump         .           .          .  ;  .210 

61  Combined  Tail-Rod  Air  and  Circulating  Pump  .  .211 

62  Steam-driven  Horizontal  Air-Pump      .           .  .  .212 

63  Direct-  Ac  ting  Air  and  Circulating  Pumps    .  .  .      213 

64  Two-Stage  Air  Pump  with  Jet  Augmentor      .  .  .      215 

65  Rotative  Air  Pump  for  Augmentor  Work    .  .  .216 

66  Air  Pump  Diagrams             .         ..          .          .  .  .      217 

Displacement  Circulating  Pump           .         ,'«.-.  .  .      219 


69  Economizer  Cross-Section   .          .          .          .         ,.          .  224 

70  Green's  Economizer,  with  Hot-water  Return        .  •        .  226 

71  Green's  Economizer,  with  Hot-  water  Return        .          .  227 

72  Economizer  with  Internal  Scrapers      .          *          .          .  228 

73  Independently  fired  Controllable  Superheater       .          .  234 

74  Independently  fired  Controllable  Superheater        .          .  235 

75  Independently  fired  Controllable  Superheater       .          .  236 

76  Weir  Feed  Heater      ......      .    .  238 

77  Row  Feed  Heater      .          .          .          .         y.          .          .  240 

78  Berryman  Feed  Heater       .....          .241 

79  Cruse  Combined  Boiler,  Feed  Heater,  and  Superheater  247 

80  Cruse  Combined  Boiler,  Feed  Heater,  and  Superheater  249 

81  Cruse  Combined  Boiler,  Feed  Heater,  and  Superheater  251 

82  Chimney  Cooling  Tower      .                               ...  261 


83  Fan  Cooling  Tower 

84  Fan  Cooling  Tower     . 

85  Spraying  Nozzle         .          .  . 

86  Weir  Feed  Pump 

87  Duplex  Feed  Pump  (Worthington) 

88  Cameron  or  Flywheel  Pump 

89  Exhaust  Injector 

90  Combined  Injector 

91  Exhaust  Injector 

92  Electrical  Oil  Separator      . 

xvi 


.  263 

.  264 

.  267 

.  278 

.  281 

.  282 

.  284 

.  285 

.  286 
302 


Section  I 

THE  TREATMENT  OF  WATER  BY 
SOFTENING,  OIL  SEPARATION 
AND  FILTRATION 


CHAPTER  I 
INTRODUCTORY 

ALL  natural  waters  contain  some  impurity,  the  amount 
of  which  depends  upon  the  nature  of  the  soil  over  or 
through  which  the  water  has  passed  between  such  time  as 
it  descended  in  the  form  of  rain  and  the  time  when  it  was 
impounded  in  some  non-soluble  vessel.  When  introduced 
to  a  steam  boiler  it  is  found  that  the  impurities  come  out 
of  solution  either  because  water  loses  its  soluble  power  at 
higher  temperatures,  or,  owing  to  evaporation  of  some  of 
the  water,  the  remainder  becomes  super-saturated  and  the 
excess  of  impurity  crystallizes  out  or  otherwise  deposits. 

As  deposited  in  a  steam  boiler,  these  impurities  take  the 
form  of  crusts  more  or  less  hard  and  adherent.  These  crusts 
are  a  source  of  trouble  more  or  less  serious  and  dangerous. 
In  the  first  place,  when  they  occur  on  heated  parts  of  the 
boiler  they  reduce  the  efficiency  of  the  transmission  of  heat 
through  the  metal  plates,  and,  if  very  thick,  the  resistance 
to  the  passage  of  heat  may  bevso  great  that  the  metal  is 
rendered  so  hot  as  to  become  reduced  in  strength,  and  a 
dangerous  condition  may  ensue,  ending  in  serious  collapse 
or  rupture  of  the  parts  overheated,  or  even  general  explosion. 

In  process  of  time  the  amount  of  deposit  becomes  so 
great  that  its  removal  becomes  imperative.  In  cleaning  a 
boiler  it  is  often  requisite  to  employ  picks,  or  the  hammer 
and  chisel,  and  in  course  of  time  the  surfaces  of  the  boiler 
become  hacked  over  like  a  coarse  rasp,  by  reason  of  the 
unskilful  use  of  the  cutting  instruments.  The  cleaning  of 
a  boiler  by  these  means  is  expensive,  and  it  is  work  requiring 
considerable  time.  Water  which  causes  deposit  necessitates, 

3 


WATER  SOFTENING  AND  TREATMENT 

therefore,  a  larger  provision  of  boilers  for  a  given  duty. 
Incrustation  has  a  powerful  influence  upon  the  design  of 
steam  boilers,  and  boilers,  otherwise  sound  in  principle  and 
good  in  practice,  may  be  barred  out  of  use  by  the  difficulty 
that  would  be  experienced  in  respect  of  cleaning.  In  con- 
sidering the  cost  of  treating  feed  water  so  as  to  prevent 
deposits  by  removing  the  impurities  from  the  water  before 
its  entrance  into  the  boiler,  there  is  to  be  set  against  the 
cost  of  treatment,  the  expense  of  cleaning,  the  waste  of 
capital  which  represents  the  reduced  life  of  the  boiler,  and 
the  interest  and  depreciation  charges  on  the  increased  plant 
which  it  is  necessary  to  employ. 

All  the  above  inconveniences  and  expenses  are  avoided 
when  a  boiler  is  fed  with  initially  pure  water,  or  water  that 
has  been  purged  of  its  impurities  by  artificial  means  ;  and 
it  may  be  added  that  pure  water  is  beneficial  in  manufac- 
turing processes,  particularly  in  the  preparation  of  high- 
class  fabrics,  the  dyeing  of  fine  wools,  especially  of  the 
fancy  order,  such  as  Berlin  wools  ;  in  brewing,  in  drug  ex- 
tracts, and  in  cleaning  and  washing  purposes.  Great  waste 
of  soap  and  detergents  is  obviated  when  pure  water  is  used. 

The  purification  of  water  for  boiler  feed  purposes  is  carried 
out  along  two  main  lines. 

First,  by  chemical  means,  such  reagents  being  added  to 
the  water  as  to  cause  sedimentation  of  the  impurities. 

Secondly,  by  the  aid  of  heat,  which  reduces  the  power  of 
water  to  hold  certain  salts  in  suspension. 

Thirdly,  may  be  named  filtration,  by  which  matters  held 
in  mechanical  suspension  may  be  removed  from  water  com- 
monly termed  dirty.  Water  of  this  kind  will  cause  deposit 
in  a  boiler  generally  of  a  softer  order  than  incrustation 
proper,  for  such  mechanically  suspended  matter  will  usually 
be  of  a  more  or  less  clayey  description.  Such  impurities 
will  deposit  in  a  large  pond  just  as  the  muddy  river  Rhone 
emerges  from  the  Lake  of  Geneva  as  a  bright  stream. 
Filtration  is  a  substitute  for  time  and  area. 

Fourthly  may  be  named  a  combination  of  the  first  and 
second  processes,  but  this  can  hardly  be  claimed  as  a  dis- 
tinct process,  the  addition  of  heat  merely  assisting  the 

4 


INTRODUCTORY 

chemical  process,  though  it  may  be  substituted  for  it  in 
certain  cases,  such  as  temporary  hard  waters. 

Properly  to  clean  a  boiler  when  it  is  laid  off  from  work 
it  should  be  left  full  of  water  until,  with  its  brickwork 
foundation,  it  has  fallen  to  atmospheric  temperature.  This 
process  can  be  hastened  by  allowing  air  to  flow  through  the 
flues  to  as  full  an  extent  as  admissible  consistently  with  not 
vitiating  the  draught  of  other  boilers  or  unduly  cooling  the 
economizer.  Without  either  of  these  possible  inconveni- 
ences, the  removal  of  back  plates  of  the  down  take  will 
help  to  cool  the  flues  of  a  boiler.  If  rapid  cooling  is  im- 
perative, the  Manchester  Steam  Users'  Association  advise 
that  cold  feed  may  be  introduced,  while  hot  water  is  run 
out  at  the  blow-out  tap.  A  boiler  should  never  be  blown 
out  under  steam  pressure  if  this  can  be  avoided.  Some- 
times it  is  necessary  to  do  this  where  the  boiler  is  below 
the  drain  level,  as  is  the  case  with  boilers  set  in  basements. 
This  can  sometimes  be  avoided  if  a  supply  of  compressed 
air  is  available  for  blowing  out  the  water,  but  the  combina- 
tion will  be  rare.  An  electrically-driven  pump  should  be 
employed  if  a  supply  of  electricity  is  available.  The  objec- 
tion to  emptying  a  boiler  when  hot  and  surrounded  with 
hot  brickwork  is  that  the  incrustation  is  dried  and  baked 
hard,  and  while  drying  it  is  exposed  to  the  action  of  the  air, 
and  may  absorb  carbonic  acid  gas  from  the  air,  and  this 
will  help  to  fix  the  deposit  more  firmly. 

Speaking  generally  of  hard  water,  the  Desrumaux  Co. 
state  that  for  every  cwt.  of  soap  used,  at  least  80  Ib.  will 
be  converted  into  the  well  known  scum  which  is  an  in- 
soluble lime  soap  that  settles  in  the  texture  of  fabrics 
washed  in  hard  water.  Since  4  Ib.  of  lime  will  soften  as 
much  water  as  80  Ib.  of  soap,  the  economy  of  softening  is 
obvious. 

They  give  a  table  compiled  from  data  supplied  by  Messrs. 
S.  Sutcliffe  &  Sons,  of  Bradford,  showing  the  soap  required 
to  soften  1,000  gallons  of  water  of  three  different  degrees 
of  hardness.  It  is  calculated  on  the  basis  of  2J  ozs.  of  soap 
per  100  gallons  per  degree  of  hardness,  or  1  Ib.  9  ozs.  per 
1,000  gallons  at  ISs.  8d.  per  cwt.  This  represents  a  loss  of 

5 


WATER  SOFTENING  AND  TREATMENT 

per  degree  of  hardness.  The  insoluble  lime  soaps 
formed  in  fabrics  cannot  be  completely  removed,  even  by 
vigorous  treatment,  and  good  dyed  tints  cannot  be  obtained 
with  hard  water  washed  goods,  nor  can  white  goods  be 
prepared.  The  lime  soaps  give  a  yellow  tint  and  also  stick 
to  dirt. 

As  compared  with  the  cost  of  boiler  compositions,  one 
chemist  states  that  where  it  cost  £177  per  year  to  soften 
33,000  gallons  a  week  from  11°  of  hardness,  the  cost  of 
chemicals  for  70,000  gallons  per  week  was  only  £35  per 
year,  or  less  than  one- tenth  the  former  cost,  and  the  water 
formerly  used  in  boilers  only  was  used  after  softening  for 
dyeing  also.  Hence  the  increase  in  the  weekly  quantity. 


CHAPTER  II 
WATER  :  ITS  SOURCES  AND  IMPURITIES 

ALL  water  has  its  origin  in  the  sea.  From  the  sea,  and 
to  a  less  extent  from  lakes  and  from  land  surfaces, 
the  sun  raises  vapour  to  form  clouds,  and  the  condensation 
of  this  vapour  produces  rain,  and  this  is  the  only  natural 
source  of  so-called  fresh  water.  In  its  descent  to  earth  the 
rain  dissolves  from  the  atmosphere  some  of  its  constituents, 
notably  carbon  dioxide  gas — C02 — of  which  four  parts  in 
10,000  of  the  atmosphere  consists,  i.e.  0-0004.  This 
gas  is  the  chief  agent  in  producing  incrustation,  because  it 
enables  water  to  dissolve  certain  salts  of  lime  and  of  mag- 
nesia. In  manufacturing  localities  the  rain  also  clears 
the  atmosphere  of  the  acids  produced  by  the  combustion 
of  coal,  of  ammonia,  and  of  solid  matters  such  as  soot  and 
wind-raised  dust ;  but  these  latter  impurities  are  not  of 
serious  importance  from  a  steam  user's  point  of  view.  Hav- 
ing fallen  to  earth,  rain  at  once  seeks  lower  levels,  and  finds 
them  by  sinking  into  the  soil  by  gravity  and  absorption, 
or  by  travelling  over  the  surface  into  streams  and  rivers. 

Approximately  of  the  rain  which  falls  one-third  runs  off 
the  surface  into  the  rivers,  one-third  sinks  deeply,  and  one- 
third  is  re-evaporated. 

In  traversing  the  surface,  water  dissolves  a  portion  of 
the  rocks  and  earths  with  which  it  comes  in  contact,  and 
the  same  when  it  sinks  to  deeper  levels  and  then  travels 
gradually  towards  the  sea  along  the  rock  planes.  The 
character  of  the  water  in  any  district  is  thus  determined 
by  the  rocks  with  which  it  has  come  into  contact.  In 
Great  Britain  the  surface  rocks  are  of  great  diversity. 


WATER  SOFTENING  AND  TREATMENT 

Generally  they  consist  of  alternations  of  clays,  sands  and 
limestones.  The  strata  forming  these  islands  are  much 
disturbed  and  inclined  downwards  at  a  considerable  angle. 
A  study  of  the  Geological  Map  of  England  will  show  that 
roughly  each  distinct  stratification  dips  towards  London, 
the  outcrops  lying  in  approximately  concentric  bands  struck 
from  a  locus  of  centres  between  Dublin  and  Belfast.  The 
various  strata  dip  successively  one  below  another,  so  that  it 
may  be  inferred  within  limits  that  a  hole  bored  at  any  spot 
will  reach  successively  the  strata  lying  progressively  to  the 
north-west  of  that  spot.  Faults  and  dislocations  and  the 
occurrence  of  rocks  which  do  not  outcrop  upset  this  general 
scheme  to  such  an  extent  that  every  case  must  be  con- 
sidered by  itself  in  the  light  afforded  by  proved  geological 
facts,  assisted  by  experience  and  aided  by  the  general  prin- 
ciples enunciated.  The  rapid  alternations  of  strata  produce 
an  equally  rapid  change  in  the  character  of  the  waters 
obtainable  in  different  areas  about  the  country. 

Speaking  generally  of  the  five  main  divisions  into  which 
the  rocks  may  be  divided,  it  may  be  said  that  these  are  Clays 
and  Marls,  Sands,  Limestones  and  Granites. 

The  clays — including  slates — and  marls  are  not  them- 
selves soluble,  but  frequently  contain  soluble  salts,  which 
are  dissolved  out  by  water.  The  marls  often  contain  lime 
salt  such  as  gypsum  or  sulphate  of  lime — CaS04 — which  is 
absorbed  by  water.  The  clays  are  represented  by  the  Lon- 
don Clay,  the  Gault  Clay,  the  Lias  Clay,  Kimmeridge  Clay, 
Weald  Clay,  Oxford  Clay,  etc.  Slates  are  clays  metamor- 
phosed by  heat  and  pressure,  and  so  are  the  shales  of  the 
coal  measures. 

The  marls  are  represented  by  the  Old  Red  Marl  and  the 
New  Red  Marl,  both  of  which  contain  gypsum,  and  by 
the  marl  of  the  Permian  Beds,  etc. 

The  sands  are  represented  by  the  Bagshot  Beds  found  on 
the  highest  points  of  the  London  Clay  area  as  Hampstead, 
Highgate,  Epping,  Laindon  Hill,  etc. ;  by  the  Lower  Green- 
sand,  the  various  beds  of  the  New  Red  Sandstone,  the 
Permian  Beds,  the  many  beds  of  the  Carboniferous  series, 
the  Old  Red  Sandstone,  and  many  of  the  older  rocks. 

8 


WATER:    ITS  SOURCES  AND  IMPURITIES 

The  representatives  of  the  limestones  are  the  Chalk,  the 
Oolites,  the  Magnesian  limestone,  the  Carboniferous  lime- 
stones and  many  beds  in  the  older  rocks. 

Granite  occurs  at  the  surface  only  in  the  west  of  the 
country,  or  in  upheavals,  as  in  the  Charnwood  Forest 
district. 

Wherever  there  is  lime  in  any  form  there  will  be  hard 
water.  Naturally  soft  water  occurs  with  the  sandstones 
and  granites  and  the  purer  clay.  Some  of  the  water  from 
these  rocks  is  so  pure  that  it  requires  no  further  purification. 

Thus  the  water  supply  of  Glasgow  is  taken  from  Loch 
Katrine,  fed  with  rain  that  has  fallen  on  non-cretaceous 
rocks,  and  it  is  quite  soft.  The  old  supply  of  Manchester  is 
obtained  from  the  Longdendale  valley,  which  is  superficially 
of  millstone  grit,  and  the  only  impurity  of  any  consequence 
to  the  boiler  user  is  a  small  amount  of  peat  acid  acquired 
from  the  peat  which  occurs  upon  the  gathering  ground. 
Many  other  of  the  northern  towns  have  a  public  water  supply 
which  approximates  closely  to  that  of  Manchester  in  origin 
and  character,  while  Birmingham  has  obtained  similar  water 
from  a  higher  barren  tract  of  land  in  Wales  of  Silurian  rock. 
The  coal  measures,  while  yielding  pure  water  from  the 
sand  rocks,  will  often  produce  very  bad  water  in  the  region 
of  the  coal  itself,  water  of  very  corrosive  acid  nature.  No 
natural  water  is  perhaps  better  than  that  from  the  Millstone 
grit,  e.g.  the  Manchester  supply  from  Longdendale. 

A  river  water  does  not  necessarily  bear  the  character  of 
the  rocks  over  which  it  runs.  The  Millstone  Grit  and  the 
Carboniferous  limestone  being  contiguous  rocks  a  river 
may  be  found  running  over  one  of  these  rocks,  while  its 
chief  sources  may  have  been  the  other  rock.  Thus  the 
course  of  the  Derwent  in  Derbyshire  is  almost  wholly  upon 
the  rocks  of  the  carboniferous  period,  yet  it  is  largely  fed 
from  the  area  of  mountain  limestone  of  which  middle  Derby- 
shire consists,  receiving  as  tributary  the  Wye,  which  with  its 
sub-streams  the  Lathkill  and  Bradford,  drain^the  Peak 
district.  The  Derwent  is  thus  by  no  means  a  soft  water 
river.  Similarly  the  Thames,  which  runs  over  a  clay  country, 
passes  through  a  chalk  area  west  of  London  and  contains 


WATER    SOFTENING   AND    TREATMENT 

some  20  grs.  per  gallon  of  lime  carbonate.  Again,  wells 
bored  in  a  sandstone  or  a  limestone  area  do  not  necessarily 
yield  water  of  a  character  corresponding  to  those  rocks,  for 
the  borehole  may  have  penetrated  into  lower  rocks  of  a 
different  order,  as  for  example  the  numerous  artesian  wells 
in  London  which  penetrate  the  London  Clay  and  the  lower 
Tertiary  Beds  and  obtain  their  water  from  the  Chalk.  At 
the  same  time  many  of  the  chalk  wells  of  London  obtain 
their  supply  from  water  which  has  reached  the  chalk  through 
the  superincumbent  bed  of  Thanet  Sand,  usually  30  to  40 
ft.  thick.  When  this  is  the  case  the  chalk  wells  of  London 
yield  a  water  of  small  hardness,  but  apt  to  be  heavily  charged 
with  salts  of  soda.  It  was  hoped  at  one  time  to  obtain 
really  soft  water  at  about  1,100  ft.  depth  in  London  from  the 
Lower  Greensand  formation,  but  this  expectation  was  dis- 
appointed, and  at  that  depth  much  older  rock,  probably  of 
Devonian  age,  was  touched,  and  further  evidence  from  sub- 
sequent deep  borings  at  Crossness,  Streatham,  Harwich, 
Ware,  Stutton,  Kentish  Town,  Turnford,  Culford,  etc.,  and 
the  coal  borings  at  Dover,  has  demonstrated  that  a  ridge  of 
old  rocks  runs  beneath  London  and  south-eastern  England 
and  has  interfered  with  the  deposit  of  newer  rocks.  The 
nearest  artesian  well  to  London  which  has  obtained  water 
from  the  Lower  Greensand  is  that  at  Winkfield,  near  Windsor, 
which  touched  the  Greensand  at  1,234  ft.  below  surface, 
entered  it  to  1,243  ft.,  and  produces  a  flow  of  water  which 
rises  to  7  ft.  8  in.  above  the  surface,  or  to  about  225  ft.  above 
ordnance  datum.  This  well,  sunk  under  the  Author  as 
engineer,  probably  draws  its  supply  from  rain  which  falls 
upon  the  outcrop  of  the  Lower  Greensand  in  the  locality  of 
Leighton  Buzzard. 

In  this  case  the  borehole  was  started  upon  a  surface  of 
London  Clay,  penetrated  the  chalk  beneath  and  the  gault, 
and  only  extracts  any  water  from  the  Lower  Greensand,  and 
the  water  is  soft.  The  instances  cited  will  be  sufficient  to 
show  to  steam  users  that  a  merely  superficial  examination 
of  their  particular  environment  is  insufficient  on  which  to 
found  a  policy  of  water  supply. 

In  originating  a  new  manufactory  it  is  too  frequently  the 

10 


WATER:   ITS   SOURCES   AND   IMPURITIES 

custom  to  consider  everything  except  the  water  supply,  and, 
when  the  money  is  spent  and  buildings  have  been  erected, 
the  water  supply  is  taken  in  hand  and  may  prove  far  more 
difficult  a  problem  than  anticipated.  In  a  case  familiar  to 
the  Author,  where  a  pure  supply  of  water  was_imperative, 
the  same  course  of  action  was  followed  out.  A^  boring  was 
then  made,  and  at  1,100  ft.  below  surface  a  supply  of  useless 
salt  water  was  obtained  andj  necessitated  heavy  payments 
for  water  from  a  source  out  of  the  control  of  the  factory. 
Though  dealing  with  the  treatment  of  water  the  advice  of 
the  Author  is  to  secure  a  supply,  if  possible,  that  does  not 
require  to  be  treated.  This  ideal  water  is  rarely  to  be 
obtained,  and  treatment  must  be  resorted  to,  but  there  must 
be  frequent  instances  where,  of  two  or  more  sites,  one  can 
be  shown  to  contain  better  prospects  of  a  suitable  water 
than  the  others,  not  merely  in  respect  of  quantity,  but  also  of 
quality.  r 

This  point  is  emphasized  because  the^strata  in  Great 
Britain  are  often  so  disturbed  that  a  very  small  difference  of 
site  may  be  of  the  utmost  importance  in  respect  of  the 
artesian  prospects,  and  the  experience  of  the  author  in  his 
capacity  of  Hydro  Geologist  has  shown  him  the  need  for 
very  careful  investigation,  especially  in  parts  of  the  country 
geologically  faulted.  In  order  to  determine  the  prospects 
of  a  supply  and  its  quality  it  is  necessary  to  make  a  close 
examination  of  the  locality  both  in  regard  to  levels  and  to 
geological  conditions.  Needless  to  say  the  water  diviner's 
art  is  not  reliable,  though  probably  some  men  who  affect  to 
discover  water  and  make  frequent  apparent  successes  have 
real  geological  knowledge,  and  they  easily  Undergo  their 
facial  contortions  and  cause  their  mystic  twig  to  jump  at 
just  such  points  as  fit  with  their  preconceived  ideas  or  actual 
knowledge.  Their  failures  are  more  numerous  than  those 
made  by  skilful  engineers  who  study  the  site  by  light  of  geo- 
logy, and  often  they  will  ignorantly  diagnose  ample  water 
supply  over  hundreds  of  feet  of  impervious  clays. 

While  for  very  large  water  supplies  large  dug  wells  are 
sunk  with  extensive  galleries  or  headings  driven  as  deeply 
as  possible  below  water  rest  level,  these  wells  are  difficult 

ii 


WATER    SOFTENING   AND    TREATMENT 

% 

and  costly  and  involve  heavy  pumping  or  the  compressed 
air  system  of  working. 

In  most  manufacturing  establishments  a  bored  tube  well 
will  be  found  sufficient.  These  are  lined  with  steel  tubes 
driven  tightly  into  the  strata  and  extending  preferably 
below  the  point  at  which  the  water  stands  during  pumping. 
When  the  water  is  below  suction  reach  from  the  surface  a 
long  deep  well  pump  is  hung  down  the  borehole.  Fre- 
quently a  borehole  may  tap  water  in  more  than  one  rock 
formation,  and  the  water  from  each  may  be  of  different 
quality.  The  less  desirable  quality  may  be  shut  out  if  there 
is  an  ample  supply  of  the  more  desirable.  Unless  of  great 
depth  and  expense  an  independent  water  supply  will  usually 
be  cheaper  than  a  public  water  supply.  But  some  of  the 
public  companies  pumping  hard  water  put  it  through  the 
Porter  Clark  process  and  soften  it  before  passing  into  their 
distribution  mains. 


12 


CHAPTER  III 
THE    SALTS    CONTAINED    IN    WATER 

THE  salts  usually  responsible  for  the  incrustation  in  a 
boiler  are  those  of  lime  and  magnesia.  These  salts, 
in  the  form  of  carbonates,  are  but  slightly  soluble  in  water, 
but  as  bicarbonates  they  dissolve  freely.  It  is  usual  to 
state  that  carbonate  of  lime  and  of  magnesia  are  soluble  in 
water  only  in  presence  of  an  additional  quantity  of  carbon 
dioxide  gas.  The  fact  that  this  gas  is  disengage&  by  boiling 
in  the  proportion  of  its  chemical  equivalent  seems  to  show 
that  it  is  as  bicarbonates  that  the  salts  named  really  dis- 
solve. The  salts  of  lime  and  magnesia  are  the  carbonates 
and  the  sulphates,  and  the  treatment  of  boiler  feed  water 
consists,  in  the  main,  in  getting  rid  of  these  two  or  four  salts 
more  or  less  completely. 

It  is  necessary  therefore  to  describe  these  salts  and  other 
impurities  of  feed  water  and  to  acquire  some  knowledge  of 
their  characteristics  and  general  properties,  before  the 
method  of  their  removal  can  be  understood.  They  are  as 
follows  : — 

Carbonate  of  Lime  or  Calcium  Carbonate  CaCO3,  or  better 
to  indicate  its  formation  CaO,CO2,  is  the  substance  that  is 
formed  when  lime  unites  with  carbon  dioxide  gas.  Lime  is 
the  oxide  of  the  metal  calcium  and  is  a  white  powder  which 
greedily  absorbs  carbonic  acid  gas  thus — Lime^CaO  + 
Carbonic  acid=C02=CaCO3  as  above.  This  salt  of  lime 
is  very  sparingly  soluble  in  water,  but  if  a  second  molecule 
of  carbonic  acid  gas  be  added  the  salt  readily  dissolves. 

Thus  CaO  +  C02  +  C03~CaQ2(C02). 
13 


WATER    SOFTENING    AND    TREATMENT 

In  nature,  lime  carbonate  is  widely  spread  and  constitutes 
the  bulk  of  the  chalk  and  of  the  mountain  limestone  forma- 
tions, and  is  indeed  the  main  constituent  of  all  limestone 
rocks,  marbles,  etc.  When  dissolved  as  bicarbonate 
there  is  supposed  to  be  present  also  a  molecule  of  water, 
=H20,  so  that  dissolved  lime  carbonate  has  the  formula 
CaO,H20,2C02. 

The  attachment  of  the  additional  molecule  of  carbon 
dioxide  is  but  feeble,  and  the  application  of  heat  is  sufficient 
to  drive  it  off  and  render  the  remaining  carbonate  of  lime 
insoluble.  Thus  it  is  that  when  a  lime  carbonate  water  that 
has  been  gradually  heated  in  an  economizer  enters  a  boiler, 
it  often  throws  off  at  once  the  additional  molecule  of  C02 
and  deposits  lime  carbonate  crystals,  CaC03,  about  the  feed 
inlet.  A  small  quantity  of  carbonate  remains  in  solution 
to  the  extent  of  only  0'03  per  1,000  of  water,  corresponding 
to  2-1  grs.  per  gallon  (10  lb.). 

Pure  carbonate  of  lime  does  not  produce  a  scale  of  great 
hardness  at  first,  but  it  hardens  with  heat  and  dryness.  It 
is  recognizable  by  the  peculiar  and  characteristic  appearance 
of  the  crystals  of  lime  carbonate  under  the  microscope.  If 
a  carbonate  water  be  heated  very  quickly  the  lime  salt  is 
more  likely  to  be  deposited  as  mud.  When  slowly  heated 
the  lime  salt  forms  the  well  known  mineral  calcite,  and, 
according  to  Stromeyer,  this  constitutes  a  hard  scale.  It 
may  do  so  when  baked  or  when  exposed  to  even  gentle 
heating  for  some  time  as  on  a  boiler  bottom,  but  when,  as 
frequently  happens,  the  passage  of  such  a  water  through  an 
economizer  just  suffices  slowly  to  raise  the  water  to  deposit- 
ing point,  the  calcite  crystals  will  separate  out  upon  the  per- 
forated feed  inlet  pipe,  and  upon  the  boiler  side  near  the 
open  end  of  a  feed  pipe,  in  large  pulverulent  masses  of 
slightly  adherent  crystals.  The  deposit  has  somewhat  the 
appearance  of  a  reddish  sandstone,  but  the  calcite  is  easily 
distinguishable  by  the  microscope.  A  boiler  must  be 
opened  up  before  its  usual  time  in  many  cases  to  clear  the 
feed  pipe  of  the  obstruction  to  the  flow  of  water.  The 
openings  to  water-gauge  taps  also  become  incrusted,  and 
may  give  rise  to  dangerously  delusive  gauge  appearances, 

14 


THE    SALTS    CONTAINED    IN    WATER 

Indeed  it  is  probable  that  these  dangers  have  been  dimin 
ished  largely  because  a  glass  gauge  is  a  condenser  and  main- 
tains a  constant  stream  of  soft  water  back  to  the  boiler 
through  the  lower  taps.  To  intensify  this  effect  copper 
bulbs  are  sometimes  connected  above  the  upper  fitting  for 
the  purpose  of  pouring  a  steady  stream  of  pure  con- 
densed steam  down  the  gauge  glass  and  through  the  lower 
cocks. 

When  other  salts  are  present  the  scale  is  modified.  The 
molecular  weight  of  lime  carbonate  is  100,  its  specific  gravity 
is  2-7.  It  combines  with  44  parts  of  carbon  dioxide,  CO2, 
to  form  bicarbonate.  If  to  water  in  which  calcium  car- 
bonate is  dissolved  by  the  influence  of  an  excess  of  carbonic 
acid  there  be  added  56  of  lime  =  CaO  for  each  100  of  lime 
carbonate,  CaC03,  held  in  solution  by  44  of  carbonic  acid — 
CO2 — there  will  be  a  total  of  200  of  simple  lime  carbonate 
formed.  The  lime  joins  with  the  carbonic  acid  gas  to  form 
carbonate  of  lime. 

Carbonate  of  magnesium,  MgC03,  is  the  same  salt  relative 
to  magnesium  that  carbonate  of  lime  is  to  calcium.  Its 
molecular  weight  is  84,  its  specific  gravity  is  2-94.  It  is 
usually  found  in  nature  in  combination  with  carbonate  of 
lime  in  the  shape  of  a  double  salt  known  as  dolomite.  The 
behaviour  is  generally  similar  to  that  of  lime  carbonate,  but 
because  of  the  smaller  atomic  weight  of  magnesium  com- 
pared with  calcium  the  molecular  weight  is  less,  and  84  of 
magnesium  carbonate  requires  an  equivalent  of  100  of  cal- 
cium carbonate.  Some  authorities  state  also  that  mag- 
nesium carbonate  is  decomposed  by  heat  into  magnesium 
hydrate  and  carbon  dioxide  thus,  MgH202+C02. 

It  is  soluble  in  water  to  the  extent  of  0'02  per  cent.  =14-00 
grains  per  gallon. 

The  salt  next  in  importance,  and  even  more  troublesome, 
is  the  sulphate  of  lime,  CaSO4,  or  CaO,SO3.  This  salt  is 
found  in  the  keuper  marls  of  the  new  red  series  and  in  the 
old  red  marls  as  gypsum.  It  was  also  found  in  the  sub- 
wealden  boring  in  Sussex,  and  it  forms  the  salt  in  the  waters 
of  Burton-on-Trent  which  gives  the  special  character  to  the, 
Burton  Ales, 

15 


WATER    SOFTENING    AND    TREATMENT 

Sulphate  of  lime,  or  gypsum,  is  found  as  a  hydrate  in 
nature,  and  if  burned  or  dehydrated  it  again  unites  with 
water  to  form  plaster  of  Paris.  As  a  boiler  incrustant  it  is 
hard  and  adhesive.  In  boilers  at  Burton-on-Trent  the  scale 
is  of  a  glistening  white,  but  underneath  the  scale  the  iron 
of  the  plates  and  rivets  is  corroded  and  oxidized.  The 
sulphate  is  readily  soluble  at  ordinary  temperatures  in 
water,  the  solubility  at  34°  C.  =  93°  F.  being  0-212  per  cent, 
or  148-4  grains  per  gallon.  At  the  boiling  point,  100°  C.  = 
212°  F.,  the  solubility  has  fallen  to  0-162  per  cent,  or  113-4 
grains  per  gallon. 

In  sea  water  there  is  considerable  gypsum,  the  solution 
being  assisted  by  common  salt.  The  molecular  weight  of 
sulphate  of  lime  is  136,  its  specific  gravity  is  2-927. 

Sulphate  of  lime  makes  a  hard  scale  because  it  does  not 
deposit  until  compelled  to  do  so  by  concentration.  At  the 
temperature  due  to  high  pressures  water  will  dissolve,  accord- 
ing to  Stromeyer,  20  grains  per  gallon.  Then,  if  the  boiler 
be  let  down  somewhat,  some  of  the  scale  redissolves  until, 
when  cold,  there  are  170  grains  per  gallon,  and  this  process 
loosens  the  scale,  which  can  be  more  readily  removed  wet. 
If  allowed  to  dry  the  concentrated  solution  in  the  body  of 
the  scale  simply  crystallizes  and  cements  the  mass  hard. 

The  slowness  with  which  the  sulphate  deposits  is  the 
cause  of  its  adhering  so  firmly  to  the  plates. 

When  there  is  sulphate  in  the  scale  it  is  doubly  important 
promptly  to  wash  out  the  boiler  while  still  wet,  and  to  keep 
it  wet  by  successive  sluicing  with  the  hose  while  in  process 
of  cleaning.  As  sulphate  is  fairly  soluble  in  pure  water  the 
use  of  a  soft  water  should  soon  begin  to  tell  on  old  sulphate 
scale,  which  will  ultimately  be  quite  removed  or  disinte- 
grated. 

Sulphate  of  magnesia,  MgS04,  is  the  salt  of  magnesia 
which  corresponds  with  the  sulphate  of  lime.  Its  molecular 
weight  is  120  and  it  is  very  soluble  in  water.  The  formation 
in  nature  of  this  salt  is  said  to  be  due  to  the  action  of  lime 
sulphate  water  on  carbonate  of  magnesia,  the  result  being 
carbonate  of  lime  and  sulphate  of  magnesia,  but  this  action 
is  reversed  when  hot  and  there  is  produced  sulphate  of  lime 

16 


THE    SALTS    CONTAINED    IN    WATER 

and  magnesium  carbonate  from  carbonate  of  lime  and  sul- 
phate of  magnesium. 

The  solubility  of  the  salt  is  24-7  per  cent,  at  0°  C.  = 
32°  F.  and  132-5  per  cent,  at  105-5°  C.  =222°  F.  Its  specific 
gravity  is  1-751  in  crystal  form. 

Waters  containing  salts  other  than  the  above  salts  are  not 
widespread.  Chloride  of  sodium  or  common  salt,  NaCl,  is 
found  plentifully  of  course  in  the  sea  and  in  the  salt  districts 
of  Cheshire  and  Worcestershire.  Nitrates  and  chlorides  are 
particularly  pernicious  in  that  they  produce  in  the  presence 
of  the  magnesium  salts  a  deposit  of  hydrated  carbonate  of 
magnesium  which  is  not  soluble,  and  of  hydrochloric  acid 
which,  in  its  nascent  state,  is  particularly  destructive  of 
boiler  plates  and  tubes.  At  high  pressures  and  tempera- 
tures this  action  is  particularly  marked,  and  has  put  out  of 
use  water  that  was  more  or  less  admissible  in  the  time  of 
lower  pressures.  High  temperature  in  fact  appears  to  ex- 
ercise a  peculiarly  bad  effect  in  decomposing  the  salts  of 
magnesia  and  the  chloride  of  sodium,  and  such  waters 
should  be  avoided  if  possible. 

In  table  I  will  be  found  a  list  of  the  chemical  and  physical 
properties  of  the  chief  impurities  of  water,  and  of  the  sub- 
stances employed  in  purification  and  formed  in  the  processes 
of  treatment. 

Speaking  in  a  general  sense  the  treatment  of  water  for 
scale  prevention  is  carried  out  along  two  lines. 

In  one,  some  substance  is  added  to  the  water  which  causes 
the  scale  forming  salt  to  become  insoluble,  when  it  may  be 
precipitated  or  filtered  out. 

In  the  other  a  salt  of  small  solubility  is  changed  into 
one  of  high  solubility  which  will  accumulate  in  the  boiler 
without  crystallizing  out  until  such  time  as  the  solution 
becomes  very  dense,  when  the  boiler  must  be  wholly  or 
partially  emptied. 

The  first  method  is  that  most  commonly  practised  because 
the  commonest  form  of  incrustation  is  the  lime  carbonate, 
CaOC02.  Dr.  Clark,  who  discovered  the  process,  has  given 
his  name  to  it. 

It  depends  upon  the  solubility  of  bicarbonate  of  lime  in 

17  c 


WATER    SOFTENING   AND    TREATMENT 

the  feed  water,  the  insolubility  of  carbonate  of  lime  and  the 
affinity  of  lime  hydrate  for  carbonic  acid  gas.  River  and 
spring  and  other  natural  waters  can  hold  bicarbonate  of 
lime  in  solution  to  a  considerable  extent.  A  quite  usual 
quantity  is  20  grains  per  gallon  =  g-^Vir  or  0-03  per  cent. 
Table  I  shows  that  carbonate  of  lime  has  only  about  one- 
tenth  this  solubility.  Dr.  Clark  reasoned  that  if  he  added 
hydrated  caustic  lime,  CaOH20,  to  water  containing  bicar- 
bonate of  lime  in  solution  he  would  convert  the  soluble 
bicarbonate  into  insoluble  carbonate,  for  the  hydrate  would 
greedily  absorb  the  second  molecule  of  carbonic  acid  gas,  and 
it  would  change  itself  also  into  insoluble  carbonate.  Thus 
both  the  lime  salt  naturally  present  in  the  water  and  that 
artificially  present  would  become  insoluble  carbonate  and 
would  precipitate  together. 


18 


CHAPTER  IV 
THE  REACTIONS  OF  SALTS  IN  SOLUTION 

UPON  the  reactions  which  occur  between  various  salts 
in   solution   depends   the   purification   that   can   be 
effected.     This  reaction,  as  it  relates  to  the  use  of  lime  as  a 
reagent,  has  already  been  referred  to  in  Chapter  III. 

Expressed  in  chemical  notation  the  action  is  as  here  re- 
presented. Under  each  substance  is  placed  its  formula  and 
its  equivalent  weight,  so  that  the  whole  process  may  be 
traced  out. 


Bicarbonate  of  Lime.  +          Slaked  Caustic  Lime. 

[CaO,C02  +  C02  }  [ 

144 

Soluble.  J  I 


144  74 

Soluble.  ) 
Carbonate  of  Lime.  +  Water. 

f2[CaO,C02]|  [H20] 

2x100  -    18  I 

[     Insoluble.     J  [  J 

In  this  reaction  a  weight  of  100  of  carbonate  of  lime  is  held 
in  solution  by  44  parts  of  carbonic  acid.  There  is  added  56 
of  caustic  lime  hydrated  with  18  of  water.  The  56  parts  of 
lime  seize  the  44  parts  of  carbonic  acid  and  convert  them- 
selves into  100  parts  of  lime  carbonate.  The  loss  of  the 
extra  44  of  carbonic  acid  leaves  100  parts  of  the  original 
matter  now  insoluble  and  200  parts  of  a  chalky  mud  are 
precipitated.  The  process  is  very  effective  and  it  is  the 
cheapest  known. 

When  water  is  analysed  for  carbonate  of  lime  the  extra 
molecule  of  carbonic  acid  does  not  appear,  and  the  analysis 
is  stated  in  terms  of  simple  carbonate  only  or  CaOCO,  ;  = 
molecular  weight  100. 

19 


WATER    SOFTENING    AND    TREATMENT 

Similarly  in  preparing  lime  water  for  treatment  no  notice 
is  taken  of  the  hydration  water,  but  the  dry  lime  is  taken 
just  as  fresh  burned  as  possible.  Thus  for  each  100  parts 
of  carbonate  of  lime  there  are  required  56  parts  of  freshly- 
burned  unslaked  lime. 

It  is  known,  say,  that  a  feed  water  contains  20  grains  per 
gallon  of  carbonate,  and  the  water  consumption  is  10,000 
gallons  per  day.  Then  10,000x20-^7,000  =  29  Ib.  nearly 
of  dry  scale  per  day  that  would  be  deposited  in  the  boilers 
or  economizers,  etc. 

This    figure    multiplied  by -5<      or  29  x  56 -^- 100  =  16'24 

Ib.  of  dry  caustic  lime  necessary  to  soften  10,000  gallons 
of  water.  The  result  would  be  nearly  60  Ib.  of  chalky  mud 
when  dry. 

Bicarbonate  of  lime,  though  given  in  Table  I  as  an  anhy- 
drous salt,  and  it  may  be  so  considered  for  convenience,  is 
not  known  in  that  form.  It  is  supposed  only  to  exist  in 
water  charged  with  carbonic  acid,  and  its  formula  then  is 
CaO,H20,2C02  =  162.  When  boiled  the  extra  volume  of 
C02  is  driven  off,  and  the  carbonate,  now  no  longer  soluble, 
becomes  mud  or  scale.  Some  processes  of  water  softening 
employ  heating  in  a  convenient  vessel  in  which  the  scale 
deposits  harmlessly  and  it  can  be  removed  at  convenient 
times. 

Carbonate  of  Magnesia. 

Next  to  carbonate  of  lime  the  common  scale-forming 
salt  is  carbonate  of  magnesia.  Except  that  its  molecular 
equivalent  is  84  instead  of  100  its  action  is  the  same  as  that 
of  lime  carbonate,  but  more  caustic  lime  is  necessary  to 
precipitate  it  in  the  ratio  of  course  of  100  :  84. 

109 
Thus  each  100  of  carbonate  of  magnesia  demands  56  x  - 

=  66 '66  of  caustic  lime  to  absorb  the  excess  of  C02,  the  result 
being  a  deposit  partly  of  magnesium  carbonate  and  partly 
of  lime  carbonate.  Expressed  in  formula  as  in  the  previous 
case — 

20 


THE    REACTIONS    OF    SALTS    IN    SOLUTION 

[Mg-CO.  +  COJ  +          [CaO]) 

(84  +  44)  +  (56)  J 

|["MgC03  +          CaCO3 

(L     84  +  100 

a  total  deposit  of  184  takes  place  where  200  took  place  in 
the  case  of  lime  carbonate. 

Carbonate  of  magnesia  usually  occurs  with  lime,  and  the 
two  are  treated  together. 

When  water  charged  with  carbonate  of  lime  enters  a  boiler 
the  water  being  already  hot,  and  the  -boiler  being,  at  say, 
350°  F.,  the  deposit  of  the  lime  is  very  rapid.  It  crystallizes 
around  the  feed  pipe  and  on  the  side  of  the  boiler  close  by, 
and  soon  chokes  the  feed  pipe  perforations.  This  is  one 
reason  why  water  ought  to  be  treated  outside  the  boiler. 

If  carbonate  of  magnesia  be  present  it  often  separates 
out  as  a  fine  flour  which  floats  for  a  time  on  the  surface  of 
the  water,  is  often  carried  off  in  priming  water,  but  is  pecu- 
liarly dangerous  when  the  feed  water  contains  grease. 

[Fortunately  when  waters  are  greasy  they  have  often  been 
purged  of  all  scale-forming  matter,  coming  as  they  do  from 
surface  condensers.] 

The  floury  deposit  combines  with  grease  to  form  a  pecu- 
liar spongy  substance,  which  will  collect  into  balls  and 
sometimes  will  collect  on  furnace  crowns.  Being  a  non- 
conductor of  heat  such  a  deposit  on  the  furnace  crown  will 
cause  overheating  and  collapse  of  the  plates.  Grease  must 
be  avoided  at  all  costs,  for  magnesia  may  still  find  its  way  in 
by  way  of  the  making  up  water. 

Except  that  magnesium  carbonate  decomposes  at  high 
temperatures  into  carbonic  acid  and  the  hydrate,  the  beha- 
viour is  that  of  lime.  This  one  difference  is  not  of  import- 
ance except  so  far  as  that  the  effect  takes  place  in  the 
feed  pipes  and  chokes  these  with  a  sort  of  gelatinous  paste. 
It  is  to  avoid  this  effect  that  water  is  recarbonized  in  the 
Archbutt-Deeley  process  to  enable  it  to  absorb  or  avoid 
such  deposits.  Water  fully  saturated  with  carbonic  acid 
can  absorb  as  much  as  70  grains  per  gallon  of  lime  carbonate. 
Distilled  water,  says  Mr.  Archbutt,  will  only  dissolve  1*3 
grains  per  gallon. 

21 


WATER    SOFTENING    AND    TREATMENT 

He  has  rarely  found,  more  than  5  to  6  grains  of  carbonate 
of  magnesia,  occasionally  twice  this  quantity,  and  once  28*8 
grains. 

He  also  states  that  sufficient  lime  must  be  added  to  a 
magnesia  water  to  decompose  the  carbonate  of  magnesia 
into  hydrate  thus — 

MgC03  +  CaOH20   =  MgO.H2O  +  CaC03. 

Soluble.  Insoluble. 

This,|ifAdone,  implies  an*  additional  quantity  of  lime  of 
66*66  Ib.  for  each  100  of  magnesia  carbonate,  or  just  double 
in  all  what  the  first  calculation  gives,  i.e.  134  of  dry  caustic 
lime  per  100  of  magnesium  carbonate.  This  is  advised 
because  it  is  considered  that  the  carbonate  is  much  more 
soluble  than  is  lime  carbonate,  but  the  hydrate  is  insoluble 
or  nearly  so.  This  further  treatment  demands  the  recar- 
bonating  of  the  finally  treated  water,  which  converts  all 
remaining  lime  and  magnesia  into  the  soluble  bicarbonate. 

In  the  year  1858  Dr.  Angus  Smith,  F.R.S.,  was  asked  to 
investigate  the  waters  used  in  and  around  Manchester  on 
behalf  of  the  Manchester  Steam  Users'  Association,  and  his 
report  was  issued  in  1859  and  has  since  been  reprinted. 
This  report  is  given  in  the  appendix,  but  it  must  be  noted, 
of  course,  that  the  one  line  of  chemical  symbols  is  not  written 
on  present  day  notation,  the  accepted  atomic  weights  being 
now  different. 

The  most  usual  salt  in  hard  water  being  carbonate  of  lime 
or  of  magnesia,  so  is  lime,  quick  or  caustic,  CaO,  the  most 
usual  reagent.  The  proper  quality  of  lime  to  employ  is  that 
known  as  fat — that  is,  it  is  a  pure  lime  free  from  clay  or  argill. 
Dorking  grey  lime,  made  from  the  lower  chalk,  is  partially 
hydraulic,  and  therefore  unsuitable.  The  upper  chalk  will 
produce  white  or  fat  lime,  and  so  also  does  the  carboni- 
ferous limestone  of  Derbyshire,  the  lime  from  which  is  sold 
under  the  generic  name  of  Buxton  lime. 

In  using  lime  it  must  be  stored  carefully,  and  should  be 
contained  in  an  air-tight  vessel  or  it  will  absorb  carbonic 
acid  from  the  air.  It  is  usual  to  slake  it  with  water  suffi- 
cient to  form  a  paste  the  day  before  use.  If  the  operation 

22 


THE    REACTIONS    OF    SALTS    IN    SOLUTION 

of  softening  is  done  by  hand  there  should  be^two  tanks,  each 
holding  not  less  than  a  day's  supply  for  use  alternately. 
The  proper  weight  of  lime  for  one  tank  of  water  after  slaking 
is  to  be  further  mixed  with  water  to  a  creamy  consistency, 
emptied  into  the  tank  and  thoroughly  well  stirred  together 
with  the  deposit,  some  of  which  must  always  be  left  in  the 
tank  from  the  previous  operation,  as  the  presence  of  this 
deposit  facilitates  the  sedimentation  of  the  new  deposit. 

When  mechanical  apparatus  is  employed  the  lime  is  mixed 
either  as  milk  of  lime  or  as  lime  water.  Milk  of  lime  is  more 
or  less  uncertain  in  its  composition  according  to  the  vigour 
with  which  it  is  kept  agitated.  Lime  water  is  a  certain 
product  which  contains  just  so  much  lime  as  water  will 
absorb,  and  it  is  thus  nominally  a  simple  matter  to  divert  a 
suitable  proportion  of  a  given  stream  of  water  through  a 
vessel  of  lime,  such  proportion  being  fixed  at  what  will  carry 
the  amount  of  lime  necessary  to  soften  the  whole. 

Thus  when  lime  is  present  in  abundance  a  passing  flow  of 
water  will  take  up  1P3  grams  of  lime,  CaO,  per  litre  or  0*13 
per  cent.  As  hi  commercial  lime  only  a  part  is  effective  it 
is  necessary  to  provide  more  lime  to  the  extent  of  about 
30  per  cent,  more  or  less.  The  use  of  lime  water  demands 
that  for  each  degree  of  temporary  hardness  about  0'55  per 
cent,  of  lime  water  must  be  employed.  This  implies  the 
division  of  the  stream  of  water  in  ordinary  cases  in  the  ratio 
of  1  :  10,  but  while  this  may  present  some  inconvenience, 
yet  it  enables  graduation  to  be  better  effected,  and  is  easily 
managed  in  mechanical  apparatus  of  the  continuous  order. 

Soda. 

This  reagent  exists  in  many  forms  more  or  less  pure.  In 
its  caustic  state,  as  NaHO,  it  is  a  solid  crystalline  substance 
dangerous  to  handle  and  very  destructive  to  the  skin,  and 
dangerous  to  the  eyes. 

Soda  Ash  is  nominally  Carbonate  of  Soda,  Na2CO3,  anhy- 
drous, and  is  rated  commercially  on  its  percentage  contents 
of  Na20. 

Dissolved  in  water  it  crystallizes,  when  evaporated  gently, 
with  10  parts  of  water  and  becomes  soda  crystal  or  common 

23 


WATER    SOFTENING   AND    TREATMENT 

washing  soda,  Na2CO3  +  10H20,  of  which  only  106  parts  out 
of  286  are  carbonate  of  soda,  and  only  about  21  per  cent,  is 
rateable  as  alkali  or  Na20. 

Caustic  soda  must  be  kept  from  the  air  as  carefully  as 
lime,  or  it  will  become  carbonate,  and  being  also  hygroscopic, 
will  ultimately  convert  itself  into  crystal  soda. 

Magnesia  as  a  Re-agent. 

As  with  lime,  so  also  with  magnesia,  may  both  lime  and 
magnesia  carbonates  be  thrown  down.  Thus — 

Lime  Lime  Magnesia 

Bicarbonate  Magnesia  Carbonate      Carbonate        Water 

(CaO,  2C02  +  MgO,  H20  =  CaCO3   +  MgCO3   +  H2O 

1      Soluble. •" 

Insoluble. 

and — 

Magnesia  Carbonate  of 

bicarbonate.  Magnesia. 

Mg02C02  +  MgO,H20  =  2MgC03  +  H20 

Soluble.  Insoluble. 

A  reaction  not  much  recognized  is  claimed  for  the  pre- 
cipitated carbonate  of  magnesia,  namely,  that  if  sulphate  of 
calcium  be  present  in  the  water  the  magnesia  deposit  will 
act  upon  it  as  follows  : — 

MgC03  +  CaS04  =  MgS04  +  CaC03 

forming  insoluble  carbonate  of  lime  precipitate  and  soluble 
sulphate  of  magnesia. 

If  no  other  salts  are  present  than  the  sulphate  and  car- 
bonate of  lime,  the  employment  of  the  magnesia  reaction 
should  produce  complete  purification  when  the  ratio  of 
carbonate  and  sulphate  lies  within  certain  limits.  But  as 
already  stated,  magnesia  must  not  be  employed  where  even 
small  quantities  of  chlorides  are  present  by  reason  of  the 
acid  corrosion  which  will  result. 

All  the  magnesium  salts  except  the  bicarbonate  produce 
permanent  hardness,  and  they  are  also  with  that  one 
exception  very  soluble.  They  are  nitrates,  chlorides 
and  sulphates,  and  they  destroy  soap. 

By  means  of  caustic  lime  and  soda  ash  Stromeyer  says 


THE    REACTIONS    OF    SALTS    IN    SOLUTION 

all  the  magnesia  salts  can  be  converted  into  insoluble 
hydrate,  with  the  formation  of  carbonate  of  lime,  etc. 

Though  lime  is  so  cheap  an  agent,  the  ordinary  boiler  user 
pins  his  faith  on  some  salt  of  soda  or  more  rarely  of  potash. 

Hydrated  caustic  soda,  HNaO,  or  hydrogen  sodium 
oxide  has,  like  caustic  lime,  a  powerful  affinity  for  carbonic 
acid  gas,  and  will  deprive  bicarbonate  of  lime  of  the  extra 
molecule  of  the  gas,  thus — 

Ca02CO2  +  2HNaO=CaC03  -f-Na2CO3  -r  H2O. 

The  carbonate  of  soda  is  very  soluble,  and  it  also  possesses 
the  power  of  decomposing  sulphate  of  calcium,  when  the 
following  interchanges  occur — 

Na2C03  +CaS04=CaC03  +Na2SO4. 

The  last  salt,  sulphate  of  soda,  remains  in  solution,  and 
can  only  be  dealt  with  by  blowing  out  so  as  to  avoid  undue 
concentration. 

Sulphate  of  magnesia  will  be  similarly  acted  upon  with 
formation  of  magnesia  and  sodium  sulphate. 

Caustic  soda,  however,  is  a  much  more  expensive  salt 
than  caustic  lime,  and  is  not  much  employed.  In  general 
good  practice  carbonate  of  soda  is  employed  in  combination 
with  caustic  lime,  thus — 

Na2C03  +  CaOH20  =CaC03  +  2NaHO, 

the  soda  being  rendered  caustic  by  the  lime,  which  is  con- 
verted into  insoluble  carbonate,  and  the  caustic  soda  pro- 
duced then  acts  on  any  carbonate  present,  and  becoming 
itself  carbonate,  is  ready  to  act  on  lime  sulphate  and  con- 
verts itself  into  sulphate  of  soda.  A  sufficient  explanation 
of  the  double  effect  will  be  found  in  Dr.  Angus  Smith's 
report  in  the  appendix. 

Soda  and  Potash  as  Carbonates. 

Carbonate  of  lime  may  be  precipitated  by  carbonate  of 
soda  in  a  continuous  manner.  The  following  reactions  are 
considered  to  occur. 

In  the  first  place  carbonate  of  soda — 

Na22C03  +  Ca02CO2  +H20=Na402,H20,3C02  +  CaCO3. 

25 


WATER  SOFTENING  AND  TREATMENT 

The  soda  salt  is  presumed  to  be  in  the  foim  of  sesquioxide 
and  to  decompose  into  Na2C03  +  H2Na22C03,  and  then  into 
(Na22C03)+C02+H20.  fj 

The  carbonate  of  soda  appears  to  possess  the  property  of 
depriving  the  carbonate  of  lime  of  the  excess  of  carbonic 
acid  which  keeps  it  in  solution.  The  highly  carbonated  soda 
salt  then  throws  off  the  carbonic  acid  free  and  attacks  a 
fresh  quantity  of  lime  carbonate.  Its  action  is  thus  succes- 
sive and  cumulative. 

With  sulphate  of  lime  and  carbonate  of  soda  or  potash 
the  result  is  carbonate  of  lime  and  sulphate  of  soda,  or 

CaS04 +NaaC08=Na2S04  +CaC03. 

Soluble  Insoluble 

Soda  has  also  a  decomposing  effect  on  calcium  chloride,  from 
which  it  produces  sodium  chloride  and  carbonate  of  lime  as 
below — 

Na2C03  +CaCl2=CaC03Na2Cl2. 

Soluble. 

The  foregoing  are  the  chief  reactions  in  ordinary  use,  and 
this  is  accounted  for  by  their  general  low  cost  rather  than 
by  their  effects,  for  there  are  equally  good  and  even  better 
effects  to  be  produced  by  other  reagents,  which  however  are 
too  costly  for  regular  trade  purposes. 

Barium  Aluminate. 

One  of  the  best  reagents  is  the  double  salt  of  barium 
and  aluminium,  Al203BaO.  With  carbonate  of  lime  the 
reaction  is  as  follows — 

Al203BaO  +  CaO,H202C02=CaC03  +BaC03  +A12O3H20. 
All   the   salts   which  result  from   this   reaction   are    very 
insoluble  and  are  precipitated.     So  with  calcium  sulphate 
the  reaction  is — 

CaS04  +  Al203BaO  =Al203CaO  +BaS04. 

Thus  no  salt  is  formed  which  remains  soluble,  and  water 
may  thus  be  purified  completely  by  the  aid  of  this  double 
salt  of  barium  and  aluminium. 

26 


CHAPTER  V 
THE  LESS  USUAL  REAGENTS 

Silicate  of  Soda. 

r  I  ^HIS  salt  will  precipitate  lime  carbonate  with  formation 
A       of  a  gelatinous  silicate  of  lime  and  carbonate  of  soda, 
thus — 

Si.03Na2  +  Ca02C02=Si03Ca  +  Na2C03  +C02, 

carbonic  acid  being  set  free.  If  sulphate  of  lime  be  also 
present,  the  carbonate  of  soda  formed  in  the  above  reaction 
then  serves  to  decompose  the  sulphate  as  well  perhaps  as  to 
act  continuously  as  explained  on  lime  carbonate. 

Silicate  of  soda  may  be  used  on  a  simple  lime  sulphate 
water,  thus — 

Na2Si.03  +  CaS04=Na2S04  +Ca.Si.03. 

M.  Taveau  says  that  600  grammes  of  silicate  of  soda  solu- 
tion of  35°  Beaume  per  horse-power  if  renewed  every  month 
will  disincrust  most  ordinary  waters. 

Oxalate  of  Soda. 

This  salt  is  expensive,  but  is  a  good  reagent.  It  forms  a 
precipitate  of  calcium  oxalate  of  a  particularly  insoluble 
nature.  Thus — 

Na2C408  +  Ca,02C02  +  CaS04=2[CaC02  +C02]  + 
Na2C03  +Na2S04  +C02. 

The  potash  oxalate  K22[C02]2  has  a  similar  action. 

27 


WATER    SOFTENING    AND    TREATMENT 

It  has  been  proposed  in  Germany  to  employ  chromate  of 
soda  or  potash  as  a  reagent  for  both  lime  carbonate  and  lime 
sulphate.  Thus  for  chrome  potash  — 


Ca02C02  ^Cr04K2=CaCrO4  +K2C03  +C02. 
For  lime  sulphate  the  reaction  is— 

CaS04  +  K2Cr04=CaCr04  +  K2SO4. 

The  chromate  of  lime  is  insoluble,  but  the  process  is  out  of 
the  range  of  practice,  for  the  chromic  alkalies  are  expensive 
and  moreover  have  a  very  high  molecular  weight,  and  to 
precipitate  a  molecule  of  lime  carbonate  of  the  weight  100 
one  molecule  of  chrome  potash  would  be  required  of  which 
the  molecular  weight  is  194*5. 

In  many  of  the  reactions  shown  in  this  and  the  preceding 
chapter  it  will  be  noted  that  a  salt  which  has  precipitated 
one  impurity  has  itself  changed,  so  that  it  is  now  in  a  form 
to  attack  a  second  impurity.  Thus  caustic  soda  will  attack 
carbonate  or  rather  bicarbonate  of  lime  and  cause  it  to  pre- 
cipitate, and  the  caustic  soda  becomes  carbonate  of  soda,  and 
will  then  precipitate  lime  sulphate  in  the  form  of  carbonate, 
and  only  sodium  sulphate  is  left  in  solution. 

Thus  CaO(C02)2  +  2(HNaO)=Na2C03  +CaC03  +H20, 
whence  CaS04  +  Na2C03=CaC03  +Na2SO4. 

As  explained  in  Dr.  Angus  Smith's  report  (see  Appendix 
No.  1)  a  water  containing  both  carbonate  and  sulphate  in 
the  ratio  of  100  of  carbonate  to  136  of  sulphate  (the  mole- 
cular weight  ratios)  can  be  exactly  treated  by  this  method. 
If  the  carbonate  is  in  excess  the  excess  of  carbonate  is  to  be 
more  cheaply  treated  by  caustic  lime.  If  the  sulphate  is 
in  excess  an  additional  amount  of  carbonate  of  soda  must 
be  added.  The  subject  is  fully  dealt  with  in  the  report 
referred  to.  ^ 

Alum  and  Alumino  Ferric. 

When  a  water  contains  organic  matter,  as  will  be  the  case 
if  it  is  sewage  polluted,  or  if  it  comes  from  an  ordinary 


THE    LESS    USUAL    REAGENTS 

river  flowing  under  healthy  conditions,  and  therefore  more 
or  less  charged  with  the  germs  of  green  plant  life,  it  will  be 
found  more  difficult  to  soften  than  a  water  from  an  arte- 
sian well  of  the  same  degree  of  mineral  impurity.  With 
such  waters  it  is  usual  to  add  a  very  small  amount  of  some 
chemical  having  the  power  of  coagulating  organic  matter. 
Such  a  substance  is  alum,  A12K24S04 +24H2O.  This  is  a 
double  salt  of  aluminium  and  potassium,  and  is  known 
otherwise  as  potash  alum.  Added  to  water  together  with 
the  usual  reagents  it  coagulates  the  organic  matter,  and 
this  facilitates  the  deposit  of  the  newly-formed  lime 
precipitates. 

Alumino  ferric  is  an  alum  in  which  A1203  is  replaced  by 
Fe203.  Its  name  is  misleading,  for  it  should  rather  be 
called  potassia-ferric,  for  it  contains  no  alumina.  It  is 
powerfully  astringent  and  is  employed  not  only  to  coagulate 
organic  matter  as  described,  but  also  in  the  process  of  sepa- 
ration of  oil  from  the  water  discharged  from  surface  con- 
densers. 


Heat. 

The  heating  of  water  is  often  made  to  do  duty  in  removing 
temporary  hardness,  leaving  the  permanent  hardness  to  iTe 
dealt  with  by  soda.  To  this  extent  therefore  heat  may  be 
almost  classed  as  a  reagent,  but.  its  complete  effect  is  only 
secured  at  the  atmospheric  boiling  point.  Inside  a  high- 
pressure  boiler  water  already  fairly  hot  when  it  enters  the 
boiler  will  reject  its  lime  carbonate  very  promptly. 

Heat,  even  if  only  a  few  degrees  temperature  additional, 
will  always  facilitate  the  discharge  of  the  C02  from  tem- 
porarily hard  water,  and  render  softening  more  complete  or 
reduce  the  time  duration  of  the  process. 

In  Chapter  X  will  be  found  further  remarks  on  the  heat 
treatment  of  temporarily  hard  water,  with  suggestions  for 
carrying  this  out  when  the  use  of  so  much  steam  is  not  per- 
missible as  in  non-condensing  steam  plants  and  where  use  is 
desirable  of  the  heat  otherwise  wasted  in  the  flue  gases  but 
available  for  feed  heating. 

29 


WATER    SOFTENING    AND    TREATMENT 

Barium  Carbonate,  etc. 

This  salt  may  be  used  for  removing  calcium  sulphate,  and, 
apart  from  its  price,  it  is  a  most  satisfactory  reagent,  for  it 
leaves  no  salt  in  the  water  as  does  sodium  carbonate,  which 
changes  into  sodium  sulphate  which  is  very  soluble,  but  in 
time  will  of  course  concentrate. 

Barium  carbonate,  BaC03,  is  itself  an  insoluble  salt  and 
cannot  be  added  in  the  ordinary  way  by  solution.  A  large 
quantity  of  the  salt  may  be  dumped  at  once  into  the  soften- 
ing apparatus,  for  no  more  will  be  taken  up  than  is  necessary 
to  take  up  the  sulphuric  acid  present  in  either  the  free  or 
combined  state.  The  products  of  the  reaction  are  barium 
sulphate  and  lime  carbonate,  both  insoluble  salts. 

The  barium  salts  being  many  of  them  insoluble,  are  thus 
excellent  reagents.  Any  carbonate  of  lime  held  in  solution 
by  carbon  dioxide  must  be  treated  by  lime. 

Barium  hydrate,  BaO,H20,  soluble  in  three  times  its 
weight  of  boiling  and  20  of  cold  water,  may  be  added  to 
reduce  permanent  hardness. 

In  comparing  this  with  soda  Mr.  McGill  says  that  300 
parts  of  soda,  Na20,  will  reduce  271  units  of  permanent 
hardness.  A  unit  of  permanent  hardness  is  1  part  of  CaO 
per  million.  Soda  ash  at  %d.  per  Ib.  of  true  carbonate,  and 
caustic  soda  at  l^d.  per  Ib.  of  true  hydrate,  involve  a  cost 
of  3'85  pence  per  1,000  gallons,  so  that  4-25  pence  may  be 
taken  as  the  outside  cost  per  1,000  gallon^.1 

To  obtain  the  same  result  with  barium  7-4  Ib.  of  the  oxide, 
equivalent  to  15*2  Ib.  of  the  crystallized  hydrate,  or 
BaOH20  +  8H20,  would  be  necessary.  Its  price  would 
have  to  be  only  0«575d.  per  Ib.  for  oxide  and  0*28d.  for 
hydrate  to  compete  with  soda.  The  lowest  price  yet  quoted 
appears  to  be  3|  times  these  figures  in  Germany,  and  2J 
times  at  Niagara.  The  barium  salt  may  ultimately  be 
electrically  manufactured  at  cheaper  rates.  The  use  of 
barium  hydrate  will  of  course  set  free  lime  hydrate,  which 
will  reduce  any  lime  carbonate  present  in  the  water  to  the 

1  Mr.  McGill  writes  from  Montreal,  so  it  is  to  be  presumed  he 
means  the  British  gallon. 

30 


THE    LESS    USUAL    REAGENTS 

insoluble  state.  Otherwise  barium  must  be  used  as  both 
hydrate  and  carbonate  in  proper  proportions  to  suit  the 
carbonate  and  sulphate  of  lime  present. 

It  requires  153  parts  of  barium  oxide  =  315  of  crystal- 
lized hydrate  to  deal  with  56  units  of  permanent  hardness, 
and  the  product  will  then  deal  with  56  of  temporary  hard- 
ness also.  At  present  treatment  by  barium  is  not  commer- 
cially practicable  as  a  rule,  but  occasions  may  happen  when 
it  could  be  used  with  advantage. 


CHAPTER  VI 


SCALE  AND  ITS  EFFECTS 

FOR  any  particular  area  of  incrusted  plate  the  presence 
of  scale  will  seriously  reduce  the  passage  of  heat  and 
plates  may  become  overheated.     But  if  only  a  part  of  a  sur- 
face be  covered  with  scale  the  efficiency  of  the  part  covered 
will  be  reduced,  but  the  clean  part  will  be  improved. 

To  show  this  idea  in  approximate  figures  Mr.  Stromeyer  1 
has  given  the  following  table  of  temperature  distribution 
in  a  boiler — 

TABLE  I. 

HEAT  DISTRIBUTION  IN  BOILERS. 


Sq.   ft.    heating 

surface  per  Ib. 

0 

i 

4 

1 

2 

4 

8 

of  fuel  per  hour. 

Flame  and  flue 

temp.  F.°     . 

3,000 

2,421 

1,961 

1,335 

728 

426 

381 

Maximum  plate 

temp.       .     . 

400 

396 

392 

387 

383 

381 

380 

Total   heat 

transmitted  % 

0 

19-8 

35-6 

57-0 

77-8 

89-2 

89-7 

Boiler  with 

scale,    £  in. 

thick. 

Flame  and  flue 

1 

temp. 

3,000 

2,484 

2,070 

1,471 

835 

459  j 

384^ 

Maximum  plate 

f 

temp. 

691 

630 

581 

510 

434 

389 

382 

Total  heat 

transmitted  % 

0 

17-5 

31-8 

52-4 

74-2 

87'0 

89-5 

1  Proc.  Inst.  M.E.,   1903. 
32 


SCALE   AND    ITS    EFFECTS 

As  boilers  usually  have  1  \  to  2  sq.  ft.  of  surface  per  Ib.  of  fuel 
per  hour  the  total  loss  from  scale  will  not  be  so  great,  and 
with  light  work  as  represented  by  4  sq.  ft.,  it  has  fallen  to 
less  than  3  per  cent.  Still  the  presence  of  scale  is  harmful. 
The  plates  are  hotter  and  the  entry  of  cool  air  produces 
greater  contraction  just  as  the  high  temperature  has  pro- 
duced a  greater  expansion,  grooving,  and  similar  forms  of 
corrosion  are  set  up  as  a  witness  to  the  movements  that  are 
in  progress,  and  these  movements  are  producing  stresses 
and  gradually  destroying  the  boiler,  and  this  alone  is  a 
sufficient  reason  for  the  use  of  soft  water. 

Grease. 

Though  introduced  with  a  nominally  clean  water  from 
surface  condensers,  grease  is  more  of  a  danger  than  scale. 
The  merest  film  of  grease  on  a  furnace  plate  will  cause  over- 
heating and  collapse,  and  though  water  may  be  deprived  of 
much  of  its  grease  by  slow  settlement  and  by  filtration 
through  sawdust,  there  is  difficulty  in  removing  all.  Com- 
bined with  carbonate  of  magnesia  grease  forms  a  peculiar 
spongy  deposit  which,  if  it  settles  on  a  furnace,  will  quickly 
produce  collapse. 

Apart  from  the  grease,  however,  the  water  from  a  surface 
condenser  has  no  impurities.  If  mixed  with  a  hard  water 
and  treated  by  some  of  the  methods  described,  the  precipi- 
tation of  the  lime  salts  will  carry  with  it  the  oil  also.  Con- 
denser water  should  apparently  be  carbonated,  well  mixed 
with  ground  chalk,  and  then  re-softened. 

Only  lime  carbonate  would  be  present  to  be  dealt  with, 
and  there  would  be  no  other  salts  to  deal  with.  It  is  most 
important  that  no  oil  should  enter  a  boiler. 

Organic  Matter. 

The  purification  of  a  well  water  free  from  organic  matter 
is  easier  to  carry  out  than  the  purification  of  water  of  the 
same  quality  after  it  has  flowed  down  a  stream.  Thus  the 
water  of  the  Thames  is  more  difficult  to  soften  than  water 

33  D 


WATER    SOFTENING   AND   TREATMENT 


from  a  chalk  well  of  equal  character,  except  for  the  organic 
life. 

The  deposit  of  the  lime  salts  is  more  slow.  This  difficulty 
is  got  over  by  means  of  alum,  as  already  described  in 
Chapter  V. 

For  any  particular  area  of  heating  surface  the  loss  of  effi- 
ciency due  to  scale  is  given  by  the  following  table — 

TABLE  II. 
Loss  OF  HEATING  POWER  DUE  TO  SCALE. 


In. 

In. 

In. 

In.      In. 

In. 

In. 

In. 

In. 

In. 

Thickness  of  Scale 

«v 

JL 

3  2 

_i_ 

1  6 

i 

JL 

1  6 

i 

i 

\ 

| 

1 

Loss  of  Heating 

Power 

2% 

4% 

9% 

18% 

27% 

38% 

48% 

60% 

74% 

90% 

These  losses  are  not  found  to  occur  in  boilers,  because  the 
whole  of  the  boiler  surface  does  not  usually  become  covered. 
Still  the  loss  is  always  serious  apart  from  the  stresses  set  up 
in  the  boiler  plates.  .e 

At  Burton-on-Trent  many  boilers  are  fed  with  water  that 
is  heavily  charged  with  sulphate  of  lime,  and  the  whole  in- 
terior of  a  boiler  up  to  the  water  line  presents  a  dazzling 
white  appearance  of  great  beauty.  If  the  scale  however  be 
attacked  with  a  hammer  and  broken  away  from  any  portion, 
as  from  a  rivet  head,  the  plate  or  rivet  will  be  observed  to  be 
in  a  rough  corroded  state,  very  black  and  exuding  a  blackish 
liquor  which  is  probably  a  compound  of  iron  with  sulphuric 
acid  from  the  scale. 

This  appearance  of  plates  under  scale  is  not  universal, 
possibly  it  is  an  attribute  of  the  more  purely  sulphate  scales, 
and  it  might  perhaps  be  corrected  by  the  use  of  an  alkali. 
But  at  Burton  any  chemical  treatment  is  debarred  so  far  as 
relates  to  any  boiler  supplying  steam  for  brewing  purposes, 
and  chemical  treatment  in  a  boiler  is  frequently  debarred  in 
other  industries  also,  and  this  is  an  argument  for  treatment 
in  separate  vessels.  The  more  entirely  carbonate  scales 
behave  differently.  A  carbonate  water  heated  well  towards 
boiling  temperature,  if  then  fed  into  a  boiler  at  about  150  Ib. 
pressure,  will  acquire  a  considerably  higher  temperature  as 

34 


SCALE    AND    ITS    EFFECTS 

it  travels  along  the  feed  distribution  pipe  and  will  promptly 
part  with  its  lime  carbonate,  which  will  collect  in  large 
masses  upon  the  feed  pipe  and  immediately  around,  and  the 
feed  will  ultimately  become  completely  enclosed  and  choked 
as  already  stated. 

The  presence  of  magnesia  seems  to  be  responsible  for  that 
fine  floury  deposit  which  gets  itself  carried  over  to  the  en- 
gines and  mixes  with  oil  in  the  boiler  to  form  a  light  spongy 
mass  that  will  cause  the  furnace  crowns  to  come  down 
should  it  happen  to  settle  on  them. 

The  most  usual  scale  is  constantly  becoming  loose  from 
the  plates,  and  as  constantly  does  it  become  re-cemented  by 
freshly-formed  scale.  Most  of  the  scale  formed  collects  at 
the  quieter  parts  of  a  boiler,  which  are,  in  the  Lancashire 
type,  the  back  end  at  the  bottom  and  along  the  lower  parts 
of  each  side  of  the  shell,  and  in  the  water-tube  type  in  mud 
drums  placed  out  of  reach  of  the  hotter  gases.  But  scale 
will  collect  in  water  tubes,  which  must  eventually  become 
burned  as  a  result,  for,  unlike  fire  tubes,  the  scale  in  a  water 
tube  cannot  automatically  break  away  from  the  metal.  On 
the  furnace  crowns  of  shell  boilers  and  on  fire  tubes  scale  as 
a  rule  is  somewhat  easily  detached,  but  the  appearance  of 
any  boiler  using  hard  water  should  be  sufficient  in  itself  to 
compel  the  owner  to  soften  the  water.  Unfortunately 
boiler  owners  are  too  rarely  acquainted  with  the  interior  of 
their  boilers,  and  do  not  therefore  attach  sufficient  weight 
to  the  representations  of  their  engineers,  and  water  softening 
is  yet  far  from  universal.  Very  often  it  is  obvious  that  the 
scale  in  some  parts  of  a  boiler  is  merely  built  up  of  bits  that 
have  separated  from  other  parts.  Thus  the  cross  tubes  that 
were  once  so  much  used  in  Lancashire  boilers  have  been 
found  choked  up  with  re-cemented  scale  of  this  nature. 


35 


CHAPTER  VII 
WATER  ANALYSIS 

THE  analysis  of  water  in  its  more  particular  aspect  is  of 
too  special  a  nature  to  justify  full  treatment  in  a 
book  of  this  nature.  The  ordinary  steam  user  will  not 
require  to  conduct  his  own  water  analysis.  The  analytical 
chemist  who  does  such  work  will  obtain  any  assistance  of 
which  he  is  in  need  from  more  strictly  chemical  treatises. 
In  a  very  large  number  of  cases  the  steam  user  who  suspects 
carbonate  of  lime  only  in  serious  amount,  as  for  example 
those  cases  which  lie  on  the  chalk  outcrop  that  extends 
over  so  much  of  the  country  south-east  of  the  curved  line 
between  Hull  and  Dorchester,  will  often  be  able  to  treat  the 
feed  water  of  his  district  by  a  trial  and  error  process,  simply 
adding  progressive  amounts  of  caustic  lime  to  a  definite 
volume  of  water  until  the  pink  reaction  with  phenol- 
pthalein  or  the  light  straw  colour  with  nitrate  of  silver,  shows 
the  alkalinity  that  proves  a  sufficiency  of  treatment. 

One  of  the  methods  of  water  analysis  is  that  which  rests 
on  the  power  possessed  by  soap  of  rendering  water  frothy 
when  the  water  is  pure,  and  of  not  producing  a  lather  so  long 
as  any  earthy  salts  are  held  in  solution,  particularly  those 
of  lime  and  magnesia.  The  soap  solution  is  made  of  a 
certain  fixed  strength,  so  that  each  unit  of  the  solution  de- 
composed by  a  hard  water  may  represent  a  definite  degree 
of  hardness. 

Standard  Soap  Solution. 

In  England  standard  soap  solution  is  made  from  Castile 
soap,  which  should  be  made  from  olive  oil  and  soda.  This 
solution,  however,  is  said  to  be  unstable,  and  sodic  oleate 
may  be  purchased  for  the  purpose.  About  13  grammes  of 

36 


WATER    ANALYSIS 

soap  are  dissolved  in  500  c.c.  of  methylated  spirits  and 
500  c.c.  of  pure  water.  1  c.c.  should  serve  to  neutralize  «001 
gramme  of  carbonate  of  lime  or  be  equivalent  to  1  degree 
of  hardness. 

To  test  the  solution  12  o.c.  of  the  standard  hard  water  are 
diluted  to  70  c.c.  in  a  burette.  To  this  is  added  1  c.c.  at  a 
time  of  soap  solution,  and  for  each  addition  the  burette  is 
shaken  until  a  five  minutes'  lather  persists.  Each  12  c.c.  of 
standard  hard  water  requires  13  c.c.  of  soap  solution,  the 
extra  1  c.c.  being  that  required  for  absolutely  soft  water. 
The  actual  figure  will  be  less  than  13,  and  the  soap  solution 
must  be  proportionately  diluted.  Thus  if  the  soap  solution 
used  is  only  12  c.c.,  each  12  c.c.  requires  diluting  by  13  -  12  = 
1  c.c. 

Standard  hard  water  is  made  by  dissolving  1-11  grammes 
of  pure  fused  chloride  of  calcium  in  water  and  diluting  to 
1,000  c.c.  at  15°  C.,  or  1  gramme  of  pure  carbonate  of  lime  is 
dissolved  in  50  c.c.  of  EHC1,1  evaporated  to  dry  ness,  dis- 
solved in  50  c.c.  of  water  and  carefully  neutralized  with 
SEAm.H.O.  Each  of  these  standards  should  for  each  c.c. 
be  equivalent  to  0*001  gramme  of  carbonate  of  lime. 

Standard  Soap  Solution  in  France. 

This  is  made  by  dissolving  100  grammes  of  white  curd  soap 
— Marseilles  soap — in  1, 600  grammes  of  alcohol  at  90°  C.  The 
soap  is  scraped  into  shreds  and  dissolved  in  the  alcohol  by 
heating  to  ebullition  point.  The  solution  is  filtered,  and  to 
it  is  added  1,000  grammes  of  pure  distilled  water. 

The  solution  before  use  is  tested  by  the  aid  of  a  solution 
of  calcium  chloride,  CaCl2,  of  4<7Tro  strength,  or  0-25  gramme 
per  litre  of  water,  or  with  a  solution  of  barium  nitrate,  of  a 
strength  0-59  gramme  per  litre.  These  are  normal  solutions. 

The  apparatus  required  is  as  follows  : — 

(1)  A  bottle  of  about  80  c.cm.  capacity  marked  at  10,  20, 
30  and  40  c.cm.  by  circular  marks. 

1  An  E  solution  is  one  containing  an  equivalent  weight  in  milli- 
grammes per  c.c.  of  water.  Thus  SE.AmH.O.  contains  175  m.g.  or 
'175  grams  in  1  c.c.  of  water  ;  35  being  the  equivalent  of  ammonium 
hydrate.  EH.C1.  means  36'5  m.g.  of  hydrochloric  acid  per  1  c.c,  of 
water. 

37 


WATER  SOFTENING  AND  TREATMENT 

(2)  A  burette  graduated  so  that  a  length  containing  2' 4 
c.cm.  shall  be  divided  in  23  equal  parts.     Each  divfsion 
represents  a  degree,  but  in  order  that  for  each  test  the 
burette  shall  be  filled  to  the  top  division,  there  is  a  space 
between  this  circular  mark  and  the  zero  division  sufficient  to 
contain  the  amount  of  soap  solution  necessary  to  maintain 
a  persistent  lather  on  40  c.cm.  of  pure  water.     The  following 
divisions  of  the  burette  then  represent  exactly  the  quantity 
of  soap  solution  destroyed  by  the  salts  in  the  water.     The 
little  extra  solution  is  necessary  to  form  a  persistent  lather 
even  with  distilled  water,  and  represents  the  amount  of 
solution  needed  by  the  water  in  any  sample  as  distinct  from 
the  salts  in  that  water. 

(3)  A  bottle  of  the  soap  solution. 

(4)  A  bottle  flask  of  distilled  water. 

(5)  A  flask  of  oxalate  of  ammonia  containing    166'66 
grammes  of  oxalate  per  litre  or  a  solution  of  ^V^h- 

(6)  A  flask  of  barium  nitrate  containing  2- 14 per  cent,  of 
azotate. 

(7)  A  pipette  divided  in  tenths  of  a  cubic  centimetre. 

(8)  A  globe  flask  gauged  by  a  circular  mark  at  the  base 
of  the  neck. 

A  spirit  lamp  and  stand,  a  glass,  a  glass  stirrer,  thermo- 
meter, and  a  flask  of  normal  solution  of  nitrate  of  barium 
(0-59  grammes  per  litre),  and  one  of  nitrate  of  silver  con- 
taining 2' 7 8  grammes  of  silver  nitrate  per  100  of  water. 

To  make  a  test  40  c.cm.  of  the  water  are  placed  in  the 
flask  and  to  it  are  added  successive  small  amounts  of  solu- 
tion from  the  burette.  The  flask  is  shaken  at  each  addition 
until  signs  of  a  lather  are  seen.  The  solution  of  soap  is  then 
added  carefully  until  the  lather  is  persistent,  when  it  should 
form  a  persistent  thickness  of  half  a  centimetre,  and  should 
last  ten  minutes  before  it  evanesces.  The  number  of  divi- 
sions of  the  burette  of  solution  which  have  been  used  are 
the  number  of  degrees  of  hardness  of  the  water. 

The  soap  solution  is  tested  for  strength  with  40  cubic 
centimetres  of  the  standard  solution  of  calcium  chloride  or 
barium  nitrate.  This  quantity  should  require  22  divisions 
in  the  burette  of  standard  soap  solution.  If  less  than  22 

38 


WATER   ANALYSIS 

degrees  are  required,  the  solution  must  be  let  down  by  adding 
about  pne  twenty-third  of  its  weight  in  water  to  correct  the 
solution  by  one  degree,  when  a  new  determination  must  be 
made  until  the  correct  solution  is  obtained. 

In  making  a  test  a  preliminary  trial  is  made  in  a  test  tube 
with  20  to  25  grammes  of  water  and  1  c.cm.  of  the  soap 
solution.  If  when  agitated  the  water  goes  milky  without 
flocculent  appearance,  the  water  can  be  tested  as  it  is.  But 
if  a  flocculent  formation  is  visible,  the  water  is  too  much 
charged  with  salt  and  must  be  diluted  by  means  of  distilled 
water,  so  that  the  diluted  mixture  has  less  than  30°  of  hard- 
ness. The  test  being  thus  made  the  result  must  be  multi- 
plied by  2,  3,  or  4  according  as  the  dilution  has  been  effected 
by  adding  1,  2  or  3  volumes  of  distilled  water. 

It  is  usual  in  particular  work  to  test  the  distilled  water, 
which  should  not  require  more  than  one  division  of  the 
burette  of  soap  solution  to  set  up  a  persistent  lather. 

If  this  is  not  so,  the  correction  to  be  made  is  x  =  (n  + 1) 
a— nA,  where  a  is  the  degree  found.  A  is  the  degree  of  the 

distilled  water,  and  -  is  the  ratio  of  mixture,  x  is  the  true 
n 

degree  of  hardness. 

To  determine  the  constituents  of  the  water  in  carbonic 
acid,  lime  salt  and  magnesium  salt,  the  following  trials  must 
be  successively  made  : — 

(a)  The  degree  of  hardness  of  the  natural  water. 

(b)  The  hardness  after  depositing  the  lime  by  means  of 
oxalate  of  ammonia. 

(c)  The  degree  of  hardness  after  having  eliminated  the 
carbonic  acid  and  carbonate  of  lime  by  boiling. 

(d)  The  degree  of  hardness  after  elimination  by  oxalate 
of  ammonia  of  the  lime  carbonate  not  precipitated  by 
boiling. 

(a)  having  been  found  as  already  described,  (b)  is  found 
by  adding  2  c.cm.  of  ^Vtn  solution  of  oxalate  of  ammonia  to 
50  c.cm.  of  water.  After  brisk  agitation  and  half  an  hour 
precipitation  the  filtered  liquor  will  be  free  of  lime  salts. 
The  hardness  is  then  found  of  40  c.cm. 

Test  (c)  is  made  by  first  boiling  gently  for  half  an  hour  a 

39 


WATER    SOFTENING   AND    TREATMENT 

fresh  sample  of  the  water  measured  in  a  gauged  bottle.  The 
original  measure  is  then  made  up  by  distilled  water  and  the 
whole  filtered  to  clear  the  deposited  lime  salt.  Then  the 
hardness  of  40  c.cm.  is  found. 

Test  (d)  is  made  by  boiling  and  filtering  50  c.cm.  of  the 
water  and  adding  2  c.cm.  of  oxalate  of  ammonia,  which  pre- 
cipitates what  lime  has  been  left  by  the  boiling.  Again 
filtering  the  hardness  of  40  c.cm.  is  found. 

From  the  hardness  c  a  subtractive  correction  of  3  is  made 
for  the  lime  carbonate,  which  does  not  deposit  by  boiling. 
The  corrected  value  is  Ci=C  —  3. 

Then  a  is  the  total  hardness  made  up  of  the  carbonic  acid 
and  all  the  salts  of  lime  and  magnesia. 

b  gives  the  salt  of  magnesium  and  the  carbonic  acid  which 
remain  after  eliminating  the  lime.  Then  a—  b  =  c=  lime 
salts. 

G!  represents  magnesium  and  calcium  salts  other  than 
carbonates,  whence  a—  GI—  e=carbonate  of  lime  and  car- 
bonic acid. 

d  finally  represents  the  magnesium  salts.  The  total 
analysis  is  thus  — 

a=C02  =     b-d     =f. 

6=CaC03  =     e-f      =  g. 


4,  ec.  =       -g 

or    =  =m' 


c=CaSO4    etc.  =     h- 
or    =    *- 
,  etc.=     %  d. 

Total         a. 

The  results  in  degrees  are  convertible  into  grammes  per 
litre  by  multiplying  by  certain  coefficients  as  follows  :— 

Chloride  of  Calcium    .      .      .  .  0-0114 

Carbonate  of  Calcium       .  .  0-0103 

Sulphate  of  Calcium  .      .  .  0-0140 

Chloride  of  Magnesium    .  .  0-0090 

Carbonate  of  Magnesium  .  0-0088 

Sulphate  of  Magnesium   .  .  0-0125 

Chloride  of  Sodium     ...  .0-0120 

Sulphuric  Acid       .      .      .      .  .      .  0-0082 

Chlorine       ........  0-0073 

Carbonic  Acid        .            .      ;  .  0-005  litre, 
40 


WATER    ANALYSIS 


Usually  no  great  error  will  be  made  if  all  lime  salts  are 
assumed  to  be  either  carbonate  or  sulphate,  and  the  only 
magnesium  salt  the  sulphate. 

Then  the  above  supposititious  sample  will  contain  : — 

of  C02  gx  0-005  litres 

Calcium  Carbonate    hx 0-0103  grammes 

Sulphate       ix  0-0140 
Magnesium     „  dx  0-0125       „ 

Approximate  determinations  may  be  made  by  weight 
with  commercial  alcoholic  soap  solution,  finding  as  above  the 
total  and  the  permanent  hardness,  diminishing  the  latter  by 
3°  as  a  correction  and  multiplying  by  0-013  grammes.  This 
gives  the  sulphates  and  chlorides  contained  in  1  litre  of 
water. 

The  difference  between  the  total  and  the  corrected  per- 
manent hardness  is  the  approximate  weight  in  centigrammes 
of  carbonates  in  a  litre  of  water. 

But  a  full  treatment  of  water  analysis  is  beyond  the  scope 
of  this  book.  Readers  who  wish  to  gain  further  informa- 
tion on  this  point  are  referred  to  works  on  chemistry,  and 
particularly  to  the  French  of  M.  A.  Taveau.1 

TABLE  in. 

SOLUBILITY  OF  GASES  AND  SALTS  IN  WATER. 


Name. 

Formula. 

Molecu- 
lar Wt. 

Solubility  per  cent, 
at  0°  C. 
and  at  100° 

Specific 
Gravity 

Oxygen 

0 

16 

O04  vols. 

— 

Hydrogen             '  . 

H 

1 

0-02 

— 

Carbon 

C 

12 

— 

— 

Sulphur 

S 

32 

— 

2 

Water    . 

H20 

18 

— 

1 

Carbonic  acid 

C02 

44 

1  8  vols.  at  0°C. 

0-9    „     ,,20°C. 

— 

Sulphuric  acid 

H2OSO3 

988 

— 

— 

Chlorine 

Cl. 

35-5 

— 

— 

Hydrochloric   acid 

H.C1. 

36-5 

— 

— 

Calcium 

Ca 

40 

— 

1-58 

1  Epuration  des  Eaux,  par  A.  Taveau,  Gauthier-Villars,  to  whom 
the  above  method  is  due. 

41 


WATER  SOFTENING  AND  TREATMENT 


TABLE   III.  (continued] 
SOLUBILITY  OF  GASES  AND  SALTS  IN  WATER. 


Name. 

Formula. 

Molecu- 
lar Wt. 

Solubility  per  cent, 
at  0°  C. 
and  at  100° 

Specific 
Gravity 

Caustic  lime 

CaO 

56 

Lime  hydrate    . 

CaOH20 

74 

0-14-0-09 

— 

„      carbonate 

CaOC02 

100 

0-0036 

2-7 

,,      bicarbonate 

CaO,2CO2 

144 

— 

— 

,,      sulphate 

CaOSO3 

136 

•0212--0162 

2-93 

,,      aluminate 

CaOAl2O3 

159 

— 

— 

„      chloride   . 

CaCl2 

111 

400 

— 

Magnesium 

Mg. 

24 

— 

1-74 

Magnesia     . 

Mg.O 

40 

0-002 

3-2 

,,           carbonate 

MgO,C02 

84 

0-020 

2-94 

„          hydrate  . 

Mg.OH2O 

58 

— 

— 

,,          sulphate 

MgOSOg 

120 

24-7-130 

1-75 

,,          chloride  . 

MgCl2 

95 

200-400 

1-56 

bicar- 

bonate 

MgOH20 

146 

— 

— 

2(C02) 

Sodium 

Na 

23 

— 

0-97 

Soda,  caustic     . 

HNaO 

40 

61 

2-13 

,,     carbonate 

Na2C03 

106 

7-45 

2-5 

„     bicarbonate    . 

HNaC03 

84 

7 

— 

„     chloride    . 

NaCl. 

58-5 

35-40 

2 

,,     sulphate  . 

Na2O.S03 

142 

5-42 

2-63 

Potassium  . 

K 

39 



0-865 

Caustic  potash 

K.H.O. 

56 

200 

2-04 

Carbonate  of  potash 

K2C03 

138 

83-153 

2-26 

Sulphate     „ 

K2OS03 

174 

10 

2-66 

Bicarbonate       ,, 

H.K.CO3 

100 

20 

— 

Chloride      „       ,, 

K.C1. 

74 

29-59 

1-94 

Barium 

Ba 

137 

— 

— 

„       chloride     . 

BaCl2 

208 

35-60 

2-66 

„       oxide   .      ; 

BaO 

153 

— 

— 

„       hydrate     . 

BaOH2O 

171 

5-10 

1-66 

„       aluminate. 

BaOAl2O3 

255 

— 

— 

,;       sulphate    . 

BaOSO3 

233 

Insoluble 

4-73 

„       carbonate 

BaOC02 

197 

»> 

— 

Aluminium 

Al. 

27-4 

2-6 

Alumina 

A1203 

103 

— 

3-9 

Aluminium 

fc 

Sulphate 

A123SO4 

343 

33-89 

1-6    ' 

Alum      .... 

A12K24S04 

517 

9*5-357 

1-72 

Ammonium 

Chloride 

HN4C1 

53-5 

35-100 



„       Carbonate 

2NH4CO3 

96 

20-volatile 

— 

„      Sulphate 

2NH4S04 

132 

66-100 

— 

42 


WATER    ANALYSIS 
TABLE  IV. 

BOILING-POINTS    OF    SALT    SOLUTIONS. 


^                                                   -. 

c.« 

W.' 

Baiium    Chloride,   Saturated    .... 

104-4 

220° 

Potassium  Carbonate        ,,          .... 

135-0 

275 

Sodium                ,,              

106-0 

222-8° 

108-4 

227-1 

The  following  is  the  form  of  analysis  asked  for  by  Mather 
&  Platt  in  connexion  with  their  Archbutt-Deeley  process. 

PARTICULARS  AND  ANALYSIS  OF  HARD  WATER. 


SOURCE  OF  SUPPLY  : 

PURPOSES  FOR  WHICH  THE  SOFTENED  WATER  is  REQUIRED  : 

ANALYSIS  :  GRAINS  PER  GAL. 

Total  Solids  (dry  at         )     .      .      .      . 

Lime  (Ca  O) 

Magnesia  (Mg  O) 

Sulphuric  Anhydride  (S  O3) 

Chlorine  (Cl) 

Alkalinity,  calculated  as  Carbonate  of 
Lime  (Ca  C  O3) 

REMARKS : 


43 


CHAPTER  VIII 
APPARATUS  GENERALLY  IN  COMMERCIAL  USE 

TO  carry  out  the  process  of  water  softening  requires  a 
certain  amount  of  apparatus,  which  must  have  space 
to  stand  in.  The  simplest  and  minimum  apparatus  consists 
of  two  tanks  each  holding  as  much  water  as  will  be  consumed 
while  the  softening  process  is  in  progress  in  the  other  tank. 
In  this  simple  system  the  reagent  already  prepared  is  added 
to  the  one  tank  of  hard  water  and  the  whole  thoroughly 
stirred  up  with  the  deposit  at  the  bottom.  Some  deposit 
must  always  be  left,  as  it  hastens  the  progress  of  sedimenta- 
tion. 

The  tank  is  then  left  to  settle,  and  the  capacity  of  the  tank 
in  use  must  obviously  be  so  great  that  it  will  serve  the  supply 
until  sedimentation  has  cleared  the  water  in  process  of 
softening  below  the  draw-off  point.  Clearly  shallow  tanks 
are  indicated,  for  a  shallow  tank  will  clear  more  quickly  than 
one  of  greater  depth.  This  system  demands  considerable 
area  and  leads  the  engineer  to  seek  for  accessory  means  of 
minimizing  space.  One  such  means  is  the  floating  take-off 
or  outlet.  This  consists  of  a  jointed  pipe  and  float  arranged 
like  a  ball  valve  float  with  an  opening  to  the  tubular  arm  of 
the  float,  maintained  just  under  the  water  surface.  Let  a 
tank  20  ft.  long  be  supposed  of  such  area  that  its  level  is 
lowered  S.inches  by  the  demand  for  water,  in  the  same  time 
that  sedimentation  goes  on  to  the  extent  of  say  4  inches. 
Then  in  one  hour  after  mixing  the  reagent  there  will  be 
4  inches  of  clear  water  in  the  tank,  and  if  the  take-off  is  then 
started  the  sedimentation  point  will  always  be  more  than 
4  inches  below  the  level  of  the  floating  outlet.  A  second 
idea  to  secure  the  same  end^would  be  to  use  a  number  of 

44 


APPARATUS    IN    COMMERCIAL   USE 

shallow  tanks  superposed.  There  are  obvious  inconveni- 
ences to  this  method,  not  the  least  of  which  is  that  the  mud 
space  at  the  bottom  of  each  tank  must  be  nearly  as  great  as 
that  at  the  bottom  of  a  deep  tank. 

The  problem  is  solved  in  practice  by  the  adoption  of  a 
continuous  process.  The  stream  of  water  to  be  softened  is 
split  into  two  streams,  one  of  which  is  turned  through  a 
vessel  containing  caustic  lime.  The  water  takes  up  a  full 
dose  of  this  in  solution  and,  passing  on,  reunites  with  the 
main  stream  in  a  suitable  mixer  which  may  be  in  the  form 
of  a  trough  with  lateral  divisions  alternately  projecting 
partly  across  the  trough  from  the  two  sides  and  serving  to 
turn  and  mix  the  water,  which  then  falls  to  the  settling  tank 
and  may  be  drawn  off  by  a  float  outlet  at  the  extreme  end 
of  the  tank.  Circulating  currents  are  stopped  by  suitable 
diaphragms.  Or  the  settling  tank  may  be  divided  into  a 
number  of  shallow  tray-like  divisions  inclined  or  horizontal, 
each  of  which  serves  to  receive  the  sediment  of  a  moving 
sheet  of  water  only  perhaps  3  or  4  inches  deep.  Sludge  taps 
serve  to  blow  out  the  deposit  when  sufficient.  All  the 
regular  apparatus  sold  on  the  market  consists  of  some  modi- 
fication or  application  of  these  principles  with  a  view  to 
effecting  complete  purification  in  a  minimum  of  space  and 
time.  Caustic  lime  can  always  be  added  in  the  way  above 
described,  for  the  proportion  of  water  can  be  adjusted  which 
flows  by  the  lime  tank,  and  if  care  is  taken  to  provide 
an  excess  of  lime  the  amount  carried  off  by  the  water  will 
always  be  a  certain  fixed  weight  per  gallon. 

For  soda  and  the  more  soluble  reagents  a  small  tank  of 
the  salt  solution  must  be  provided  that  will  run  empty  in 
about  the  time  necessary,  or  some  means  provided  so  that 
in  a  continuous  process  the  correct  amount  of  soda  is 
added. 

In  some  apparatus  the  chemicals  of  all  sorts  are  added  in 
a  dry  state  to  the  water  by  means  of  a  measuring  wheel 
rotated  by  the  water  supply,  the  chemicals  being  mixed  by 
agitation  before  the  water  reaches  the  depositing  tank. 

When  a  carbonate  water  is  first  treated  the  carbonate  of 
lime  separates  out  in  a  colloidal  condition  like  thin  blue 

45 


WATER  SOFTENING  AND  TREATMENT 

starch,  and  this  will  pass  through  filters  untouched.  Later, 
and  more  quickly  if  heated,  it  begins  to  crystallize,  and 
according  to  Professor  Wanklyn,  will  settle  through  f  inch 
of  water  in  twenty-five  minutes,  and  it  requires  eight  hours 
to  settle  20  inches  when  cold.  Mixing  in  old  deposit 
hastens  the  action,  and  it  is  assisted  by  bringing  in  the 
freshly- treated  water  from  below. 

Magnesia  is  even  more  gelatinous  than  the  carbonate  of 
lime.  Even  with  large  apparatus  some  sediment  fails  to 
deposit,  and  many  apparatus  employ  a  finishing  filtration  of 
closely  woven  cotton  bags,  wood-wool  or  sponge,  the  most 
efficient  being  perhaps  those  in  which  the  water  flows  up- 
wards against  the  filtering  surface,  and  the  deposit  is  free 
to  drop  off  by  gravity  or  to  be  forced  off  occasionally  by  a 
reverse  flow. 

In  mixing  lime  water  about  97  grains  of  caustic  lime  will 
dissolve  in  water  at  32°  F.  =0°  C.,  91  grains  per  gallon  at 
59°  F.=15°  C.,  70  grains  at  111°  F.=44°  C.,  and  only  40 
grains  at  212°  F.=100°  C.  According  to  the  temperature 
of  the  water,  so  must  the  proportion  sent  through  the  lime 
tank  be  divided.  Soda  is  recommended  by  Mr.  Stromeyer 
to  be  best  supplied  by  an  iron  pump  from  a  tank  in  which 
from  time  to  time  a  definite  weight  of  soda  is  put  with  a 
definite  volume  of  water.  Weirs,  scoop  wheels,  cocks  are  all 
used,  and  the  division  of  the  supply  to  the  lime  tank  may  be 
made  by  a  shifting  plate  of  metal  movable  so  that  a  different 
proportion  may  be  made  to  pass  either  side  as  required.  All 
these  and  other  details  are  found  in  some  or  other  of  the 
various  apparatus  described  in  Chapter  IX. 

No  matter  what  chemicals  may  be  selected,  the  apparatus 
employed  will  be  the  same.  The  principle  enunciated  by 
Dr.  Clark  underlies  the  action  of  all,  and  all  apparatus 
represents  after  all  different  ways  of  carrying  out  the  same 
thing.  | 

In  selecting  a  few  only  out  of  the  many  the  author  wishes 
to  disclaim  any  intention  of  putting  any  apparatus  forward 
as  better  than  others  not  mentioned.  Those  described  are 
put  forward  as  types  or  variants  of  a  general  design,  and  will 
appeal  to  users  in  proportion  as  their  particular  arrangement 


APPARATUS    IN   COMMERCIAL   USE 

or  mechanism  suits  the  conditions  which  the  user  may  have 
to  meet. 

It  is  necessary  to  state  these  facts,  because  there  are  a 
large  number  of  apparatus,  and  this  book  is  not  a  catalogue 
of  the  whole  number,  and  in  brief  some  few  must  be  chosen 
for  the  purpose  of  description,  and  those  selected  happen  to 
have  most  readily  come  under  the  author's  notice  at  the 
time  Chapter  IX  was  written. 

The  cost  of  water  softening  plant  per  1,000  gallons  treated 
per  hour  may  be  generally  set  down  at  £100  to  £150,  the 
smaller  plants  costing  more  per  unit  of  capacity  than  larger 
plants.  As  with  soft  water  a  boiler  may  be  worked  continu- 
ously for  long  periods,  it  will  be  cheaper  to  lay  down  a 
softening  plant  than  to  put  down  a  spare  boiler,  which 
would  be  required  in  the  absence  of  the  plant.  Thus  in  every 
way  the  softening  of  water  will  produce  a  handsome  return. 


47 


CHAPTER  IX 

EXAMPLES  OF  WATER-SOFTENING  APPARATUS 

The   Archbutt-Deeley  Process 

IN  this  process,  in  addition  to  the  softening  process  there 
is  a  further  treatment  of  the  softened  water  with  car- 
bonic acid  gas  for  the  purpose  of  preventing  the  subsequent 
deposit  in  the  pipes  of  a  peculiar  gelatinous  hydrate,  which 
is  found  frequently  to  occur  and  chokes  the  pipes. 

To  prevent  this  deposit  the  softened  water  is  charged 
with  carbonic  acid  gas  produced  in  a  coke  stove,  and  the 
particles  of  lime  or  magnesia  which  would  deposit  in  the 
pipes  are  converted  into  bicarbonates.  The  water  is  thereby 
again  naturalized  or  it  acquires  a  small  degree  of  temporary 
hardness. 

For  3,000  gallons  per  hour  or  less  one  softening  tank  and 
a  storage  tank  are  necessary. 

For  10,000  gallons  per  hour  not  fewer  than  three  tanks 
are  needed. 

Hard  water  being  turned  into  one  tank,  Figs.  1,  2,  3,  the 
caustic  lime  and  carbonate  of  soda  are  weighed  out  and 
boiled  together  in  the  little  chemical  tank  by  means  of  live 
steam.  The  large  tank  having  now  filled  to  a  gauge  mark 
the  inlet  valve  is  closed  and  a  steam  blower  or  aspirator  is 
put  into  action  to  draw  water  from  about  the  middle  height 
of  the  tank  and  deliver  it  through  a  horizontal  perforated 
pipe  placed  about  four-fifths  down  the  tank  depth.  Into 
the  pipes  of  this  circulating  system  the  chemical  solution  is 
allowed  slowly  to  run  and  the  chemicals  are  evenly  diffused 
throughout  the  tank.  This  done,  any  alumino-ferric  is  run 
in  in  the  form  of  a  standard  solution.  Air  is  then  admitted 
to  the  steam  blower  and  a  three-way  cock  being  reversed, 


WATER-SOFTENING   APPARATUS 


49 


WATER    SOFTENING   AND    TREATMENT 

the  air  is  discharged  into  the  bottom  of  the  tank  through 
perforations  in  the  lower  side  of  a  pipe  laid  along  the  tank 
bottom.  This  air  stirs  up  the  old  deposit  left  in  the  tank 
for  about  ten  minutes,  and  in  an  hour  the  tank  will  have 
cleared  to  a  depth  of  perhaps  6  ft.  The  water  is  then  tested 
by  adding  a  few  drops  of  a  solution  of  silver  nitrate  to  some 
of  the  water  in  a  small  white  basin. 

If  too  little  lime  has  been  employed,  the  water  will  turn 
milky  white  ;  if  too  much,  a  dark  brown  colour  will  be  pro- 


FIG.  2.     END  ELEVATION. 


duced.  Correctly  treated  water  will  show  a  faint  straw 
colour,  and  so  long  as  this  is  perceptible  the  less  of  it  the 
better.  Water  is  drawn  off  by  a  hinged  floated  pipe, 
into  which,  at  the  upper  end,  is  forced  by  a  steam  blow 
carbonic  acid  gas  from  a  small  stove.  The  gas  is  carried 
down  the  pipe,  which  is  rectangular  and  fitted  with  baftle 
plates,  and  re-carbonates  the  water  in  the  process.  The 
finished  product  is  discharged  into  the  small  supply  tank. 

A  final  test  of  the  water  is  made  by  means  of  phenol- 
phthalein,  which  will  turn  pink  in  water  containing  free 

50 


WATER-SOFTENING   APPARATUS 


WATER  SOFTENING  AND  TREATMENT 

alkali  but  remains  unchanged  if  there  is  the  least  trace  of 
carbonic  acid  in  excess.  Re-carbonating  is  not  always 
necessary. 

The  mud  deposited  in  the  softening  tank  is  variously 
removed  by  a  sludge  cock,  by  sweeping  it  through  mud  doors 
or  by  raising  it  with  a  steam  lifter  into  a  cart  containing 
furnace  ashes,  which  let  the  water  pass  and  intercept  the 
chalky  mud. 

The  apparatus  described  is  made  by  Mather  &  Platt,  to 
whom  is  due  the  Table  V.,  showing  the  estimated  cost  of 
softening  a  number  of  different  waters  per  1,000  gallons. 

While  some  waters  are  costly  to  soften,  it  is  well  remarked 
that  the  costliness  is  often  a  measure  of  the  necessity,  and 
that  it  may  still  be  cheaper  to  soften  a  bad  water  than  to 
purchase  water  which  may  be  little  or  nothing  better  and 
must  still  be  softened. 

It  is  indeed  a  bad  water  that  costs  3d.  per  1,000  gallons 
to  soften  and  few  public  water  supplies  can  be  purchased 
for  even  6d. 

In  Table  VI.  are  given  the  dimensions  of  tanks  necessary 
for  various  quantities  of  water  to  be  treated  per  hour.  The 
figures  are  based  on  the  conditions  enunciated  at  the  head 
of  each  division  of  the  table. 

The  steam  used  by  the  blower  only  raises  the  temperature 
of  the  water  about  2°  F.  and  is  not  all  lost,  for  it  returns 
more  or  less  to  the  boiler. 


,  -*  co  co  ,     ,     ,  oo  co 

??<?  M       ?«? 

^  CM  00  >0 

1O  CM  CM 


^  10  >0         -« 

CO  CM  CO 


i  c»  os    i 
^    1  <N  »b    1 


os  9   I  10   I  9  9 

10     I    ^     I    CM  10 

CM  -H          i-H 


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CS 
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t-OJ 


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r^iocs    I     I     I  cb 


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i  CO  i  CO  CO  CO 
I  co  I  '  co  • 


CS  CO 
O5  !>• 
O  <N 


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I    CS  •*  OS     I       I      I    CM  CO 

'    CM  CM  00     I  '    «b 


OS    — 


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-T9 

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21 121  I  ill 


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(M  CO 


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co  oo 
A  <jb 

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l>  00          »O 

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00 

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10  CM 


s 


s 


Total  Lime  (Ca  O)  . 
Total  Magnesia  (Mg  O 
CALCULATED  HARDNE 
and  Magnesia,  calc 
of  Lime) 


Chemicals  req 
gallons 


e  Cos 
ng  1, 


Approxi 
for  sof 


53 


WATER    SOFTENING    AND    TREATMENT 


TABLE  VI. 

SHOWING  NUMBER  AND  SIZE  OF  TANKS  REQUIRED  FOR  VARIOUS 
QUANTITIES,  UNDER  ORDINARY  CONDITIONS. 

Tank  calculated  to  fill  in  twenty  minutes,  and  to  empty  in  twenty 
minutes  into  reserve  tank,  allowing  ninety  minutes  for  treating 
and  settling. 


CAPACITY. 

Hard  Water 

Diam. 

Gallons 

Number  and  approximate  Dimensions 
of  Tanks. 

Supply 
required 
per  min. 
Gallons. 

D!  CUM. 

of  Inlet 
Pipes. 

of 
Outlet 
Pipes. 

hour. 

600 

.  .     7'  0"  X     7'  0"  X     7'  0" 

70 

3" 

3" 

1,000 

.  .    8'  0"  x    8'  0"  x    8'  0" 

120 

4" 

4" 

1,500 

.  .12'0"x    8'0"x    8'0" 

180 

4" 

5" 

2,000 

.  .  12'  0"  x    8'  0"  x  10'  0" 

240 

5" 

6" 

2,500 

.  .  12'  0"  x  10'  0"  x  10'  0" 

300 

6" 

6" 

3,000 

..12'0"xl2'0"xl0'0" 

360 

& 

7" 

Each  tank  calculated  to  fill  in  twenty  minutes,  and  to  give  continuous 
delivery,  allowing  ninety  minutes  for  treating  and  settling. 


4,000 

2..12'0"xl2'0"xlO'0" 

360 

6" 

4" 

5,000 

2.  .13'  6"x  13'  6"x  10'  0" 

450 

7" 

4" 

6,000 

2.  .15'0"x  15'0"x  10'  0" 

560 

8" 

4" 

7,000 

2..  16'  6"  x  16'  6"  x  10'  0" 

680 

8" 

5" 

8,000 

2.  .17'  6"x  17'  6"x  10'  0" 

765 

9" 

5" 

9,000 

2..  18'  6"  x  18'  6"  x  10'  0" 

855 

10" 

5" 

10,000 

2..  19'  6"  x  19'  6"  x  10'  0" 

950 

10" 

5" 

12,500 

3.  .15'  6"x  15'  6"x  10'  0" 

600 

8" 

6" 

15,000 

3..17'0"xl7'0"xlO'0" 

720 

9" 

6" 

17,500 

3.  .18'  0"x  18'0"x  10'  0" 

810 

9" 

7" 

20,000 

3.  .19'  6"x  19'  6"x  10'  0" 

950 

10" 

7" 

25,000 

3..  21'  6"  x  21'  6"  x  10'  0" 

,160 

10" 

8" 

30,000 

3.  .23'  6"x23'  6"xlO'  0" 

,380 

12" 

9" 

35,000 

4..21'0"x21'0"xlO'0" 

,100 

10" 

9" 

40,000 

4.  .22'  6"x22'  6"x  10'  0" 

,270 

12" 

10" 

45,000 

4.  .24'  0"x24'  0"x  10'  0" 

,400 

12" 

10" 

50,000 

4..25'0"x25'0"xlO'0" 

,560 

12" 

12" 

60,000 

4.  .27'  6"x27'  6"x  10'  0" 

,850 

14" 

12" 

In  cases  where  the  supply  available  is  only  equal  to  the  demand, 
larger  tanks,  or  more  of  them  than  given  above,  are  required. 


54 


WATER-SOFTENING   APPARATUS 

The  Criton  Apparatus. 

This  apparatus  is  made  by  the  Pulsometer  Engineering 
Co.,  Ltd. 

In  this  apparatus  the  quantities  of  the  reagents  delivered 
are  measured  by  the  displacement  of  plungers,  the  sub- 
merged bulk  of  which  can  be  accurately  adjusted  to  give  the 
required  proportions  of  reagents  to  hard  water,  and  cannot 
afterwards  vary  from  any  accidental  cause.  Neither  the 
lime  water  nor  the  softened  water,  before  settlement,  passes 
through  ball  valves  or  other  openings  liable  to  choke. 

The  amount  of  reagent  displaced  can  be  varied  in  a  few 
seconds  by  means  of  the  nuts  which  govern  the  submersion 
of  the  plungers. 

The  proportion  of  reagents  to  hard  water  remains  the 
same,  no  matter  at  what  speed  the  plant  is  run,  and  the 
speed  of  the  plant  is  controlled  by  a  single  valve  on  the  hard- 
water  inlet. 

The  reagents  and  the  hard  water  are  admitted  at  the 
same  time  and  place,  and  thorough  mixing  is  thus  secured. 

Complete  removal  of  suspended  matter  is  obtained  by 
the  use  of  a  filter  with  a  granular  filling. 

This  filter  bed  is  cleaned  by  a  reverse  current  of  water, 
thus  avoiding  the  trouble  and  expense  of  removing  the 
dirty  filtering  material  for  washing  or  renewal. 

The  attention  required  is  that  of  one  man  for  half-an-hour 
to  an  hour  once  every  twelve  hours,  according  to  the  size 
of  the  plant. 

Reference  to  the  diagram  (Fig.  4)  shows  that  the  hard 
water  is  supplied  intermittently  by  means  of  a  syphon  trap 
in  the  upper  float  tank. 

A  float  in  this  top  tank  actuates  a  displacement  plunger 
in  the  lime  tank  and  a  smaller  plunger  in  the  little  soda 
tank  which  is  kept  full  of  soda  solution  by  means  of  a  ball 
valve. 

The  lime  tank  which  contains  an  excess  of  lime  is  kept 
full  by  a  ball  valve,  water  entering  at  the  conical  base  and 
rising  through  the  lime. 

While  the  hard  water  is  filling  the  top  syphon  tank  the 

55 


HORD  WATER INLE. 


FIG.  4.     THE  CHITON  WATER  SOFTENER  (Pulsometer  Co.). 

56 


WATER-SOFTENING   APPARATUS 

lime  and  little  soda  tanks  are  filled  by  their  respective  ball 
valves  and  when  the  syphon  discharges  to  the  mixer  the 
float  falls  and  depresses  the  lime  and  soda  plungers  and  the 
chemicals  flow  to  the  mixer  in  even  proportion  with  the  hard 
water.  The  mixer  discharges  by  a  down  pipe  to  the  base  of 
the  settling  tank,  stirring  up  the  older  deposit  there  and 
precipitation  is  facilitated  by  this  and  by  the  precipitate 
constantly  descending  from  the  upflowing  water. 

The  settling  tank  discharges  at  the  top  into  the  filter. 


The  Doulton  Apparatus. 

In  this  apparatus — the  low  form  of  which  is  illustrated 
in  Fig.  5 — the  hard  water  enters  by  a  ball  valve  over  a  water 
wheel,  which  drives  the  stirrer  at  the  bottom  of  the  reagent 
tank. 

The  day's  supply  of  chemicals  is  placed  in  a  hopper  through 
which  the  reagent  tank  is  filled  from  the  stop-cock,  thus 
forming  a  saturated  solution,  the  supply  of  which  is  auto- 
matically regulated  in  the  following  manner  : — 

The  hard  water  flows  from  the  tank  containing  the  water 
wheel  into  the  Regulating  Box,  thereby  raising  a  float,  which 
opens  a  valve  and  permits  the  solution  from  the  reagent 
tank  to  flow  in.  The  hard  water  and  reagents  then  mix 
together  by  means  of  the  swirl  made  in  the  circular  funnel 
leading  to  bottom  of  settling  tank  ;  there  all  impurities  are 
deposited.  The  softened  water  finally  rising  through  the 
filter  bed  to  the  outlet. 

Should  the  supply  of  hard  water  cease  or  be  reduced,  the 
float  will  lower  itself,  and  thus  regulate  the  flow  of  reagent 
automatically  in  proportion  to  the  water  to  be  treated,  as 
shown  in  Fig.  6. 

The  reagent  and  settling  tanks  are  provided  with  sludge 
cocks  and  pipes  for  cleansing  purposes,  and  all  working 
parts  are  accessible  by  means  of  the  platforms  and  ladders 
as  shown. 

Softeners  have  all  the  same  action  and  are  variously 
adapted  according  to  the  waters  to  be  treated.  The  low 
shapes  are  designed  for  use  where  height  is  limited  and, 

57 


FIG.  5.     THE  DOULTON  SOFTENER  (Doulton  &  Co.). 


FIG.  6.     DOULTON  SOFTENER  (DETAIL  OF  MIXER). 

58 


WATER-SOFTENING   APPARATUS 

ground  space  available  (or  for  special  positions,  such  as  on 
joists  over  boilers),  whilst  the  tall  shapes  are  for  use  where 
ground  space  is  limited  and  height  available.  These  latter 
can  be  made  to  deliver  at  any  height  required,  and  the  low 
shape  can  be  designed  to  suit  any  available  space. 

These  softeners  require  attention  once  a  day  for  filling 
in  reagents,  which  occupies  very  little  time,  and  for  which 
no  skilled  labour  is  necessary. 

In  the  automatic  cut-off  arrangement  just  referred  to 
(Fig.  6)  the  hard  water  is  delivered  through  the  pipe  M  into 
the  regulating  box  G  and  passes  out  through  the  shute  in 
front  of  same,  in  its  passage  raising  the  float  W  and  con- 
sequently opening  the  reagent  valve  L  to  an  amount  pro- 
portionate to  the  quantity  of  water  passing  through  box  G. 
The  reagent  is  supplied  through  the  pipe  U  and  the  tank  Y, 
the  regulator  N  and  valve  L  ;  thus  a  definite  quantity  of 
reagent  is  supplied  to  a  definite  quantity  of  water,  the  re- 
agent falling  into  the  mouth  of  the  shute  Q.  They  are  mixed 
by  being  whirled  round  the  standing  outlet  V,  over  which 
the  water  and  reagent  fall  and  are  led  by  the  pipe  R  to  the 
bottom  of  the  settling  tank. 


TABLE  VII. 

APPROXIMATE  SIZES  OF  DOULTON  APPARATUS. 
LOW  SHAPE. 


To  Soften. 

300  galls,  per 

500 

800 
1,500 
2,000 
4,000 
6,000 


Ground  Space. 

Total  Height. 

hour,     8 

ft. 

0 

in.    by    5 

ft. 

0 

in. 

8 

ft. 

d 

in. 

10 

ft. 

0 

in. 

6 

ft. 

0 

in. 

9 

ft. 

3 

in. 

12 

ft. 

0 

in. 

7 

ft. 

0 

in. 

8 

ft. 

8 

in. 

13 

ft. 

0 

in. 

10 

ft. 

0 

in. 

10 

ft. 

-2 

in 

15 

ft. 

0 

in. 

10 

ft. 

0 

in. 

11 

ft. 

6 

in. 

17 

ft. 

0 

in. 

12 

ft, 

0 

in. 

14 

ft. 

6 

in. 

20 

ft. 

0 

in. 

14 

ft. 

0 

in. 

15 

ft. 

•2 

in. 

TALL    SHAPE. 


To  Soften. 

400  galls,  per  hour, 
1,200 

2,000        „ 
4,000 
6,000 


6  ft.  0  in. 

8  ft.  0  in. 

9  ft.  0  in. 

12  ft.   6  in. 

13  ft.  0  in. 

59 


Ground  Space, 
by 


4  ft.  0  in. 

5  ft.   6  in. 


Height  of 
Delivery. 

10  ft.   6  in. 
18  ft.   0  in. 


6  ft.  0  in.  23  ft.  0  in. 
6  ft.  0  in.  27  ft.  6  in. 
6  ft.  0  in.  34  ft.  6  in. 


WATER  SOFTENING  AND  TREATMENT 

The  above  sizes  can  be  varied  to  suit  any  available  posi- 
tion. They  are  given  for  softeners  worked  on  lime  and 
carbonate  of  soda  principle,  to  serve  as  a  general  guide  to 
the  floor  space  and  height  requirements  of  softening 
apparatus. 

The  Guttmann  System. 

This  system  (Fig.  7)  is  worked  by  the  Babcock  &  Wilcox 
Co.  of  London.  It  combines  heat  treatment  for  dealing 
with  the  temporary  hardness  and  soda  to  treat  the  per- 
manent hardness. 

The  apparatus  consists  in  the  main  of  a  soda,  tank,  a 
reaction  tank,  a  filter  box  and  soft-water  tank  which  is  so 
arranged  that  the  drawing  off  of  soft  water  regulates  the 
amount  of  soda  added  to  the  incoming  stream  of  hard  water. 
The  process  is  thus  of  the  continuous  order.  The  filter  is 
usually  wood-wool. 

The  apparatus  can  be  used  with  any  softening  process, 
employing  either  lime,  caustic  soda,  or  other  chemical ;  but 
the  use  of  carbonate  of  soda  (alkali),  or  of  mono-silicate  of 
soda,  is  preferred. 

Either  exhaust  or  live  steam  can  be  employed.  When 
exhaust  steam  is  available  this  is  utilized  for  heating  the 
water  to  a  temperature  of  180°F.  to  200°  F.,  thus  effecting 
a  saving  in  fuel  consumption.  A  small  amount  of  live  steam 
is  sometimes  required  to  bring  the  temperature  of  the  water 
up  to  boiling  point. 

The  apparatus  is  thus  a  water  softener  and  feed- water 
heater  combined,  the  pure  water  being  fed  into  the  boilers 
at  a  high  temperature. 

Grease  contained  in  the  exhaust  steam  is  trapped  by  the 
wood-wool  in  the  filter  tank. 

The  apparatus  occupies  space  as  below — 

Quantity  treated  Length.  Width.  Height, 

per  Hour.  ft.     in.  ft.     in.  ft.     in. 

300  Gallons         .  .  13    10  .  .  3  0  .  .  7  6 

1,000     do 13     10  ..  3  6  ..  8  0 

3,000     do 160  .  .  5  3  .  .  10  6 

6,000     do 17      4  ..  5  3  .  .  13  0 

10,000     do 194  . .  7  6  .  .  16  0 

60 


WATER-SOFTENING   APPARATUS 


61 


WATER    SOFTENING   AND    TREATMENT 

As  shown  in  Fig.  7,  it  consists  of  a  tank  A,  into  which  the 
chemical  required  for  the  day  is  put,  and  the  tank  is  then 
filled  with  water.  Underneath  is  the  reaction  tank  B.  The 
hard  water  enters  at  E,  the  admission  being  controlled  by  a 
valve  which  is  actuated  by  a  rod  F,  connected  to  the  float  G 
in  the  soft- water  storage  tank  K.  A  similar  valve,  con- 
nected to  the  same  float,  controls  the  admission  of  the 
chemical  solution,  and  between  this  valve  and  the  chemical 
tank  a  cock  is  interposed  to  provide  for  any  variation  in 
the  strength  of  the  chemical  solution  or  in  the  composition 
of  the  water.  The  hard  water  and  soda  solution  in  the 
reaction  tank  are  raised  to  boiling  point,  and  at  the  same 
time  thoroughly  agitated  by  means  of  one  or  more  steam 
injectors  C. 

The  water  then  flows  over  a  weir  into  the  filter  tank  D, 
which  has  divisions  reaching  alternately  to  within  a  few 
inches  of  the  bottom  and  top,  forming  compartments,  which 
compel  the  water  to  take  a  zig-zag  course.  A  perforated 
plate  H  forms  the  bottom  of  each  compartment,  which  is 
filled,  as  a  filtering  medium,  with  wood-wool  compressed  to 
the  required  density  ;  a  similar  perforated  plate  being 
placed  on  the  top  of  the  wood-wool  in  each  compartment. 
Below  the  bottom  perforated  plates  is  a  settling  chamber 
for  the  interception  of  sludge,  which  is  removed  by  opening 
the  blow-off  cocks  attached.  Thus  a  free  passage  way  is 
provided  for  the  water,  which  leaves  the  filter  in  a  perfectly 
clear  state  and  flows  into  the  storage  tank  K,  from  whence 
it  can  be  drawn  off. 

The  following  example  shows  the  results  obtained  with 
East  London  water  :— 

Hard  Water,         Softened  Water, 
grains  per  gallon,     grains  per  gallon. 

Temporary  hardness       .      .      .      .      14-2      '    .  3'7 

Permanent  ,,  3»1          .  none 

Total  „  ....      17-3        V  3-7 

Of  the  3 •?  grains  per  gallon  2-7  grains  are  further  pre- 
cipitated by  prolonged  boiling  in  the  boiler  itself  ;  the 
remaining  1-0  grain  represents  the  solubility  of  calcium  and 
magnesium  carbonates. 

62 


The  following  test  is  advised  by  the  makers  to  show 
whether  the  proper  amount  of  soda  solution  is  being  em- 
ployed — 

A  piece  of  litmus  paper  of  neutral  tint  is  dipped  into  the 
last  compartment,  say,  twice  a  day.  Upon  withdrawal,  the 
litmus  paper  should  show  a  very  faint  blue  colour,  indicating 
that  the  water  is  slightly  alkaline  ;  if  a  darker  colour  is 
shown,  less  soda  solution  should  be  employed  ;  if  no  colour, 
more  solution  should  be  run  in. 


The  Baker  Apparatus. 

This  is  an  apparatus  of  the  type  which  divides  the  treated 
water  into  numerous  thin  sheets  for  the  purpose  of  reducing 
the  distance  through  which  deposit  has  to  take  place. 

Fig.  8  represents  the  apparatus  in  elevation.  The  hard 
water  enters  by  the  pipe  A  and  passes  on  to  the  tank  B 
which  is  partitioned  and  contains  in  one  part  the  soda  solu- 
tion, and  in  the  other  part  the  hard  water,  each  compart- 
ment being  provided  with  a  valve  which  regulates  the  flow 
of  liquid  into  the  proportioning  or  measuring  tank  C.  This 
measuring  tank  C  has  four  compartments,  and  receives  a 
constant  supply  of  (1)  hard  water  to  be  softened,  (2)  of  lime 
water,  and  (3)  of  soda  solution,  the  fourth  compartment 
being  open  to  the  flow  of  liquids  from  the  three  other  com- 
partments, but  when  the  storage  cistern  is  full  (not  shown) 
a  valve,  operated  by  a  float,  closes  at  the  bottom  of  this 
fourth  compartment.  The  closing  of  this  valve  stops  the 
flow  of  the  liquids  above-named  until  the  level  of  softened 
water  in  the  storage  tank  is  lowered.  The  mixture  of  the  hard 
water  with  lime  water  and  soda  solution  immediately  becomes 
turbid  and  passes  down  two  sides  of  the  settling  tank  EE 
by  the  segmental  spaces  PP,  the  heavier  portion  of  the  pre- 
cipitate falling  immediately  into  the  cone  H  at  the  bottom 
of  the  settling  tank,  whence  all  deposits  are  discharged  at 
intervals  by  opening  the  flushing  valve  J. 

After  passing  down  the  two  spaces  PP  the  turbid  water 
passes  up  into  a  central  space  V  and  branches  off  right  and 
left,  rising  at  an  angle  between  the  louvres  of  settling  plates 

63 


WATER    SOFTENING    AND    TREATMENT 

GG,  which  are  about  two  inches  apart,  so  that  the  sediment 
has  only  two  inches  of  vertical  distance  to  fall  between  each 


FIG.  8.     THE  BAKEB,  SOFTENER  (Baker). 

pair  of  plates,  and  the  settlement  in  even  this  small  depth  is 
claimed  to  be  hastened  by  the  attraction  of  the  plates  for 


WATER-SOFTENING   APPARATUS 

the  particles  in  suspension  ;  consequently  the  passage  be- 
tween each  pair  of  settling  plates  is  found  to  clarify  the 
formerly  turbid  water,  which  then  passes  upward  through 
a  fibre  filter  R,  finally  passing  out  at  the  delivery  pipe  S, 
which  may  be  connected  either  to  a  storage  tank  or  to 
service  pipes.  The  preparation  of  lime  water  is  effected  in 
the  vessel  DD  which  is  fitted  with  a  perforated  tray  at  K 
upon  which  the  lime  is  placed,  and  where  it  gradually  dis- 
solves and  is  constantly  stirred  up  from  the  conical  bottom 
of  the  vessel  by  means  of  a  current  of  air  and  water  which 
passes  down  by  the  pipe  L. 

The  clear  lime  water  rises  to  the  top  between  the  external 
cylinder  D  and  the  internal  cone,  overflowing  in  a  measured 
stream  to  the  measuring  tank  C.  A  valve  M  at  the  bottom 
of  the  cone  discharges  undissolved  lime  and  other  impurities 
which  settle  there. 


The  Reisert  Softener. 

The  action  of  this  apparatus  will  be  evident  from  the 
illustration  (Fig.  9).  It  consists  of  a  lime  saturator  S,  a 
soda  chamber  N,  a  water-distributing  tank  R,  lime  being 
slaked  in  the  right-hand  division.  There  is  a  reaction  tank 
D  and  a  filter  F  which  is  self-cleansing.  The  conical  shape 
of  the  vessel  S  ensures  a  quick  mixing  action  of  the  water 
which  enters  by  way  of  the  pipe  V  and  a  slow  final  move- 
ment which  enables  undissolved  lime  particles  to  settle 
back  and  leave  the  effluent  clear  to  flow  by  the  pipe  W  to 
the  reaction  chamber  D  by  way  of  the  mixing  pipe  E. 

The  soda  apparatus  N  acts  as  follows.  Whereas  lime 
dissolves  only  in  a  definite  proportion,  there  is  almost  no 
limit  to  the  solubility  of  soda.  A  quantity  of  soda,  there- 
fore, that  will  suffice  for  one  day,  is  dissolved  all  at  once  in 
the  chamber  N.  The  action  of  the  soda  apparatus  is  based 
on  the  fact  that  the  soda  solution  has  a  greater  specific 
gravity  than  water. 

The  water  flows  from  the  distributing  tank  R  through 
the  micrometer  valve  M — which  is  adjusted  in  accordance 
with  the  amount  of  soda  required — into  the  soda  chamber  N 

65  F 


WATER   SOFTENING   AND  .  TREATMENT 

and  remains  always  on  the  surface  of  the  soda  solution  (no 
mixing  occurs)  and  displaces  the  same,  through  the  small 


Water  supply 


refuse 

FIG.  9.     THE  REISERT  SOFTENER  (Royle).  % 

pipe  from  the  bottom  upwards,  and  into  the  mixing  pipe  E, 
and  finally  into  the  reaction  chamber  D. 

R  is  the  water-distributing  tank,   and  is  supplied  with 
the  hard  water  to  be  treated  by  pipe  and  cock  as  shown  ; 

66 


WATER-SOFTENING    APPARATUS 

it  is  also  provided  with  an  overflow  pipe.  It  is  further 
provided  with  three  micrometer  valves  at  an  equal  height, 
first  P  for  the  inflow  of  the  untreated  water,  the  second  V 
for  the  lime  water,  and  the  third  M  for  the  soda  chamber. 
By  arranging  these  three  valves  at  an  equal  height,  the 
quantities  of  water  flowing  from  them  are  always  propor- 
tionate or  simultaneous  and  cease  flowing  in  the  event  of 
the  water  supply  ceasing  altogether. 

From  the  lime-slaking  division  R2  the  lime  paste  is  con- 
veyed in  bulk  to  the  bottom  of  the  lime-saturator  S  through 
the  short  depending  pipe. 

The  reaction  chamber  T)  thus  receives,  through  the  pipe  E, 
the  untreated  water,  lime  water  and  soda  water. 

The  water  now  overflows  via  the  pipe  H  into  the  filter 
chamber  F  following  the  course  of  the  arrows  downward 
through  the  filter  bed  and  upwards  through  the  pipe  T  into 
t  Je  reserve  tank  X,  in  its  course  keeping  constantly  full  the 
small  tank  X1.  The  height  of  the  column  of  water  in  the 
pipe  H  will  vary  with  the  resistance  of  the  filter  bed,  and 
as  the  latter  becomes  foul  the  water  will  rise  higher  in  H. 
Similarly  it  will  rise  to  an  equal  height  in  the  annular  pipe  Q. 
Within  the  pipe  Q  a  pipe  L  is  arranged  as  shown,  and  as 
soon  as  the  resistance  through  the  filter  bed  reaches  such  a 
point  as  to  cause  the  water  to  overflow  this  pipe  L  a  SYPHON 
action  is  started,  and  instantly  reverses  the  current  through 
the  filter  bed,  drawing  backwards  the  clear  water  held 
in  the  small  tank  X1  and  thus  automatically  cleansing 
the  filter,  the  sediment  being  discharged  at  L  into  the 
gulley  A.  The  small  tank  X1  is  proportioned  to  hold  suffi- 
cient water  thoroughly  flush  to  the  filter  F  and  as  soon  as 
the  tank  is  empty  air  enters  via  the  pipe  T  and  destroys 
the  syphonic  action.  The  filter  then  resumes  its  normal 
action  and  so  continues  until  the  fouling  is  again  such  as  to 
cause  the  pipe  L  to  overflow  when  the  cleansing  action  is 
repeated. 

The  filtering  material  does  not  require  renewing  and  never 
wears  away. 


WATER    SOFTENING   AND    TREATMENT 

The  Bruun-Lowener  System. 

In  this  apparatus  the  water  to  be  treated  is  led  by  a  pipe 
into  one  of  the  chambers  of  an  oscillating  receiver  C. 

When  this  chamber  is  filled  the  receiver  tips  over,  pouring 
its  contents  into  the  intermediate  tank  B  below,  and  bring- 
ing the  other  chamber  of  the  receiver  below  the  orifice  of  the 
pipe  K.  Above  the  oscillating  receiver  is  a  semi-circular 
tank  D,  containing  the  chemicals,  and  in  the  bottom  of  this 
tank  is  a  valve  through  which  the  chemicals  fall  into  the 
chamber  of  the  oscillating  receiver.  The  receiver  at  every 
oscillation  actuates  the  valve  in  the  bottom  of  the  tank  D 
through  a  system  of  levers.  The  lift  of  the  valve  is  regulated 
by  two  nuts  fixed  on  the  valve  spindle,  so  that  a  given 
quantity  of  chemicals  can  be  mixed  with  the  water. 

The  lime  milk  in  this  apparatus  has  a  strength  of  10  per 
cent.  ;  the  lime  water  used  in  other  apparatus  has  only  an 
average  strength  of  0'13  per  cent.  ;  the  lime  milk  therefore 
has  a  strength  of  nearly  100  times  that  of  the  lime  water, 
making  it  possible  to  reduce  the  size  of  the  tanks  containing 
the  lime  in  the  same  proportion.  A  further  advantage 
claimed  for  lime  milk  is,  that  a  certain  quantity  of  fresh 
burnt  lime  is  mixed  with  a  certain  quantity  of  water,  a 
solution  being  obtained  the  strength  of  which  is  always 
known. 

In  order  to  keep  the  lime  milk  in  constant  motion  an 
agitator  is  fixed  inside  the  semi-circular  vessel  containing 
the  chemicals,  and  the  oscillation  of  the  receiver  C  is  utilized 
for  driving  the  agitator. 

The  water  and  the  chemicals  in  the  mixing  tank  B  are 
kept  in  motion  by  means  of  a  plate  S,  fixed  to  the  bottom  of 
the  receiver  C.  The  mixture  then  passes  from  B  into  the 
heating  chamber  H,  which  is  provided  with  a  steam  nozzle 
for  either  live  or  exhaust  steam.  The  water  is  generally 
heated  to  a  temperature  of  about  150°  F.  to  facilitate  the 
precipitation  of  the  foreign  matters.  Where  steam  is  not 
available  the  water  can  of  course  be  treated  cold. 

From  the  heating  chamber  the  water  passes  through  the 
by-pass  pipe  G  into  the  settling  tank  A,  where  precipitation 

68 


WATER-SOFTENING    APPARATUS 
takes  place.     Before  leaving  the  tank  the  water  is  passed 


through  the  filteu  I,  which  is  filled  with  wood-wool,  packed 
tightly  between  two  rows  of  wooden  bars.     The  filter  can 

69 


WATER    SOFTENING    AND    TREATMENT 

be  taken  out  and  cleaned  by  removing  the  top  bars,  and  the 
filtering  material  can  be  used  over  and  over  again,  after 
having  been  properly  cleansed.  A  sludge  cock  F  is  pro- 
vided for  drawing  off  the  deposit. 

The  softened  and  purified  water  coming  from  the  filter 
flows  into  the  storage  tank  0  at  the  end  of  the  softener  and 
is  drawn  therefrom.  The  flow  of  water  to  the  oscillating 
receiver  is  regulated  by  means  of  a  high  pressure  ball  valve  P 
fixed  on  the  pipe  K. 


The  Desrumeaux  Apparatus. 

This  apparatus  (Figs.  11,  12)  consists  of  three  parts,  viz., 
a  saturator,  a  soda  or  reagent  tank  and  a  settling  chamber. 

The  saturator  is  usually  a  cylindrical  tank  into  which  a 
portion  only  of  the  water  is  admitted.  It  contains  a  mixer 
actuated  by  a  small  water  wheel  driven  by  the  water  to  be 
softened.  The  lime  water  is  supplied,  therefore,  fully  satur- 
ated with  lime,  for  the  water  to  be  saturated  rises  up  through 
the  lime  and  past  the  rotating  mixing  blades  or  arms. 

The  soda  tank  is  fitted  with  a  device  which  scoops  up  a 
definite  quantity  of  soda  solution  to  suit  the  amount  of 
water  passing  over  the  small  water  wheel.  The  lifter  being 
worked  by  the  wheel  is  thus  automatically  regulated.  The 
mixed  water  finally  passes  to  the  base  of  the  settling  tank 
and  travels  upward  between  the  blades  or  plates  of  multiple 
spiral  cones  arranged  at  such  an  angle  that  the  deposit  will 
slide  down  the  blades  and  drop  to  the  base  of  the  vessel, 
whence  it  is  discharged. 

The  illustration  (Fig.  12)  makes  this  more  clear  than 
words.  The  correct  action  depends  simply  upon  the  diver- 
sion of  a  suitable  proportion  of  the  water  through  the  lime 
tank  and  the  correct  regulation  of  the  soda  lifter.  Once  fixed 
the  process  should  continue  correctly  so  long  as  the  quality 
of  the  water  remains  constant.  The  mixing  of  the  two 
waters  takes  place  in  the  vertical  central  tube  of  the  settling 
tank. 

A  filter  of  wood-wool  is  placed  at  the  top  of  the  settling 
tank  to  remove  the  last  trace  of  deposit. 

70 


WATER-SOFTENING    APPARATUS 


FIG.   11.     THE  DESRUMEAUX  SOFTENER. 
71 


WATER    SOFTENING    AND    TREATMENT 


FIG.   12.     THE  DESRUMEAUX    SOFTENER.     SECTION    OF    DEPOSIT   TANK- 

72 


WATER-SOFTENING    APPARATUS 

The  action  of  the  plant  is  as  follows  : — A  definite  amount 
of  lime,  which  is  ascertained  by  test,  is  placed  in  the  lime 
tank  and  slaked.  When  thoroughly  slaked  this  is  let  down 
to  the  bottom  of  the  saturator,  through  a  valve  on  the  lime 
tank.  If  the  water  requires  soda  treatment  a  certain  weight 
of  soda  ash  is  placed  in  the  soda  tank  and  dissolved.  On 
the  water  being  let  into  the  distributing  tank,  part  is  diverted 
into  the  cup  on  the  top  of  the  central  tube  of  the  saturator, 
whence  it  passes  to  the  bottom  of  saturator  and  rises  through 
the  lime.  As  more  water  enters,  the  water  gradually  rises 
in  the  saturator,  until  it  overflows  at  the  top  as  clear  satu- 
rated lime  water,  which  passes  by  a  trough  into  the  central 
tube  of  the  decanter.  The  remainder  of  the  water  which 
enters  the  distributing  tank  falls  over  the  water  wheel,  thus 
actuating  the  lime  agitators  at  the  bottom  of  saturator  and 
also  the  soda  delivery  gear.  This  water  then  falls  down 
the  central  tube  of  decanter  where  it  becomes  intimately 
mixed  with  the  lime  water  and  soda  solution.  On  reaching 
the  bottom  of  the  decanter  it  passes  upwards  through  the 
settling  plates,  and  through  the  filter,  and  flows  out  at  the 
top  ready  for  use.  The  greater  part  of  the  precipitated 
matters  is  deposited  on  the  settling  plates,  whence  it  gravi- 
tates to  the  conical  mud  chamber,  from  which  it  can  be 
removed  by  opening  the  purging  valve. 

The  apparatus  treats  the  water  cold,  and  is  continuous 
in  its  action,  and  special  note  is  made  of  the  ease  by  which 
the  precipitated  matters  and  waste  lime  are  flushed  out. 

Average  London  water  usually  costs  in  reagents  about 
0'5  of  a  penny  per  1,000  gallons  treated. 

Average  London  water  is  practically  filtered  Thames  water, 
some  of  the  supplies  being  considerably  reinforced  by  water 
from  chalk  wells. 


The  Stanhope  Water-softening  Apparatus. 

The  Stanhope  apparatus  (Fig.  13)  is  one  which  carries 
out  the  continuous  process  and  is  arranged  for  automatic 
regulation,  the  water  supply  being  divided  into  suitable 
proportions  before  passing  through  the  reagent  tank  or  to 

73 


WATER    SOFTENING   AND    TREATMENT 

the  mixing  tank.  Thus  the  reagent  solution  is  saturated 
lime  water  and  the  soda  solution  is  measured  off  by  the 
lime-mixing  gear  which  is  driven  by  a  water  wheel  actuated 
by  the  actual  water  entering  the  apparatus.  This  wheel 
keeps  the  lime  constantly  agitated  and  ensures  saturation 


DIVIDING  TANK 


FIG.    13.     THE  STANHOPE  SOFTENER  (The  Stanhope  Co.). 

of  the  portion  of  water  which  flows  through  it.  The  l^me 
mixer  is  a  small  pump-chain,  as  shown  in  the  illustration, 
except  that  in  the  present  type  of  apparatus  the  up-running 
chain  is  inside  a  pipe  and  is  thereby  more  efficient. 

The  water  from  this  and  from  the  soda  tank  falls  with 
the  main  supply  into  a  mixing  vessel  and  some  of  the  deposit 

74 


WATER-SOFTENING    APPARATUS 


per  hour 

.  .  .  9 

.  .  .  11 

ft. 
ft. 
ft, 

ft! 

x 

.•' 
K 

X 

5 

6 
8 

24 

ft. 
ft. 
ft. 

ft' 

1 
j 

For    small    type 
plant  rectang- 
•  ular  tanks. 

circular 
tanks. 

• 
» 

?> 

.  .  .  14 

!  !  .  20 

is  there  deposited,  the  water  thence  flowing  to  the  base  of 
the  settling  tank,  up  which  it  slowly  rises  through  the  per- 
forated cones  which  are  steeply  inclined  so  as  to  shed  the 
deposit,  which  they  receive,  towards  the  central  tubes  which 
convey  it  to  the  base  of  the  vessel.  Above  the  cones  is  a 
filter  box  of  wood-wool. 

The  ground  area  occupied  by  the  apparatus  is  approxi- 
mately as  below  :— 


1,000 
2,000 

2,000 
6,000 
8,000 
10,000 


The  figures  of  cost  given  by  the  Stanhope  Co.  are  that 
each  degree  of  hardness  destroys  1-7  lb.  of  best  hard  soap 
per  1,000  gallons,  in  addition  to  the  soap  that  really  does 
duty  as  a  detergent.  Washing  of  a  fabric  does  not  take 
place,  in  fact,  until  the  water  lathers  freely  and  to  produce 
the  beginning  of  a  lather  destroys  the  above  amount  of  soap. 

One  pound  of  lime  w^ll  soften  as  much  water  as  4|  lb.  of 
soda  carbonate,  or  17  lb.  of  hard  soap. 

The  relative  cost  at  ordinary  prices,  is  : — with  lime,  1  ; 
soda  carbonate,  50  ;  soda  hydrate,  30  ;  soap,  500. 

Not  only  is  soap  costly,  but  the  product  it  forms  is  a  scum 
and  cannot  be  removed  by  settlement.  It  is  also  sticky 
and  disagreeable. 

A  water  of  16°  of  hardness  can  be  softened  by  lime  and 
soda  to  3°  for  an  average  cost  of  one  penny  per  1,000  gallons. 
This  would  cost  3<s.  6d.  in  soap. 

London  water  requires  20  lb.  of  soap  per  1,000  gallons 
more  than  the  water  supplied  to  Glasgow  or  Manchester 
and  other  of  the  northern  towns. 

The  soda  is  regulated  neither  by  a  cock  nor  by  a  dipper. 
A  small  portion  of  the  hard  water  passes  by  a  special  nozzle 
from  the  inlet  tank  into  the  soda  tank  by  two  outlets  which 
move  up  and  down  on  a  pivot,  and  are  governed  by  a  large 

75 


WATER  SOFTENING  AND  TREATMENT 

hydrometer  in  a  second  compartment  of  the  soda  tank  ; 
according  as  the  soda  solution  (which  runs  out  past  the 
hydrometer)  is  strong  or  weak,  the  hydrometer  tilts  the 
outlets  so  that  the  water  either  goes  direct  to  the  solution 
and  dilutes  it  or  goes  direct  to  the  soda  and  so  strengthens 
the  solution.  The  effect  is,  that  the  soda  solution  is  always 
of  the  same  effective  strength,  the  requisite  strength  being 
determined  by  weights  on  the  hydrometer. 

The  Wollaston  Apparatus. 

In  this  apparatus  (Figs.  14,  14a)  the  process  is  continuous. 
The  hard  water  is  delivered  down  a  cascade  or  modification 
of  a  salmon  ladder  and  preferably  meets  a  flow  of  exhaust 
steam  which  helps  to  facilitate  the  chemical  reactions.  The 


FIG.   14.     WOLLASTON  APPARATUS  (DIAGRAMMATIC).^ 

reagents  are  fed,  as  is  also  the  total  water,  by  means  of 
pumps  geared  together  to  a  suitable  speed.  The  mixed 
waters  fall  on  a  centrifugal  mixer  A  and  then  descend  to 
the  base  of  the  settling  tank  and  away  by  the  pipe  B  to  the 


WATER-SOFTENING   APPARATUS 

clarifying  tank  C,  in  which  its  course  is  deflected  to  and  fro 
over  the  edges  of  the  inclined  shelves  D,  which  catch 
deposit  and  discharge  it  as  indicated  in  the  figure  to  the 
bottom,  whence  it  is  discharged. 

Probably  all  these  continuous  apparatus  would  be  quick- 
ened in  action  if  supplied  with  a  means  of  returning  some 
small  portion  of  the  old  sludge  to  the  hard  water  inlet  so  as 


"•  S/udye 


Part   Sectional    Elevation 

FIG.  14a.     WOLLASTON  APPARATUS. 


Sludge 
Cross  Section  of  Clarifying   Tank. 


to    provide  the  nuclei  which  are  found  to  facilitate  the 
crystallization  of  freshly  formed  deposit. 

In  a  modification  of  the  Wollaston  apparatus  the  same 
pump  forces  water  to  both  the  lime  solution  tank  and  to 
the  mixing  tank,  through  a  valve  that  is  so  geared  to  the 
pump  that  for  each  100  strokes  any  desired  proportion  of  the 
strokes  deliver  entirely  to  the  lime  tank  and  the  remainder 

77 


WATER  SOFTENING  AND  TREATMENT 

entirely  to  the  mixing  tank.  The  relative  proportions  are 
thus  very  positively  determined.  The  soda  pump  is  also 
positively  geared  in  correct  ratio  with  the  hard  water  pump 
so  as  to  ensure  correct  treatment. 

The  Carrod  Apparatus. 

This  apparatus  which,  like  others,  works  on  the  lime  or 
lime  soda  process,   according  to  the  degree  of  temporary 


FIG.  15.     THE  CARROD  SOFTENER. 

78 


WATER-SOFTENING   APPARATUS 

or  permanent  hardness,  is  put  forward  as  occupying  little 
space.  A  capacity  of  100,000  gallons  per  day  calls  for  a 
floor  space  18  ft.  by  10  ft.,  and  a  height  of  18J  ft. 

The  operation  is  of  the  continuous  order  and  automatically 
adjusts  itself  upon  the  opening  of  the  water-supply  valve. 

The  mixture  tanks  at  the  top  of  the  apparatus  (Fig.  15) 
are  in  duplicate,  the  mixtures  being  prepared  in  one  tank 
while  the  other  is  being  used.  The  proportion  of  water 
diverted  to  the  reagent  tanks  is  decided  by  the  size  of  the 
nozzles,  the  flow  through  which  is  kept  constant  by  the 
constant  head  maintained  in  the  tanks  by  ball  float  valves. 

The  Paterson  Water  Softener. 

The  Paterson  Engineering  Company  are  the  makers  of 
the  water  softener  (Fig.  16).  Lime  and  soda  are  the  soft- 
ening  reagents  used.  The  hard  water  enters  through  an 
inlet  controller  into  an  automatic  chemical  supply  apparatus, 
in  which  it  is  measured  continuously,  in  its  passage  through 
a  narrow  vertical  discharge  weir,  described  later.  Along- 
side the  main  re-action  tank  there  is  a  lime  water  saturator. 
The  measured  water  necessary  to  form  the  lime-water  passes 
down  the  central  pipe  to  the  tapered  bottom  of  the  saturator, 
and  in  its  passage  upward  through  the  cream  of  lime,  with 
which  the  conical  bottom  has  been  charged  from  the  slaking 
tank  carried  overhead,  it  becomes  a  clear  saturated  solution 
of  lime,  and  as  such  flows  into  the  mixing  box.  The  supply 
of  soda  is  drawn  from  the  storage  tank  by  a  floating  outlet 
and  thence  thfough  a  ball  valve  to  the  chemical  supply 
apparatus. 

The  hard  water,  soda  and  lime  water  are  mixed  in  the 
mixing  box,  pass  down  an  external  drop  pipe,  shown  dotted, 
and  thence  into  the  precipitating  chamber,  tangentially. 
Here  the  precipitation  of  the  bulk  of  the  impurities  is  facili- 
tated by  dividing  the  water  into  thin  films  over  a  series  of 
inclined  settling  plates.  The  semi-purified  water  then 
passes  upwards  through  a  preliminary  strainer  of  wood  fibre 
contained  in  the  annular  space  between  the  quartz-sand 
filter  and  the  shell  of  the  main  tank. 

The  quartz- sand  filter  is  for  removing  the  last  trace  of  oil 

79 


WATER    SOFTENING    AND    TREATMENT 


tHLETOF  HARD  WATER 


FIG.  16.     THE  PATERSON  WATER  SOFTENER  AND  GREASE  ELIMINATOR. 

80 


WATER-SOFTENING    APPARATUS 

and  finely  suspended  matter.  The  filtering  medium  em- 
ployed is  a  specially  prepared  quartz  silver  sand  resting 
upon  a  bed  of  fine  pea  gravel.  The  filtered  water  is  drawn 
off  by  a  large  number  of  finely  perforated  gun-metal  strainers, 
screwed  into  the  manifold  pipe  system  leading  to  the  pure 
water  outlet. 

The  filter  bed  is  cleaned  by  reversing  the  current  of  water 
through  it,  the  impurities  overflowing  into  the  annular 
gutter,  and  thence  through  a  waste  pipe  to  the  drain.  An 


FILLING   UP  PIPt 


FIG.   16A.     DETAIL  OF  REGULATING  APPARATUS. 

air  compressor  assists  this  process,  by  thoroughly  agitating 
and  aerating  the  filtering  medium. 

The  automatic  chemical  supply  regulating  gear  is  shown 
enlarged  in  Fig.  16a. 

The  hard  water  enters  the  chamber  A  through  the  inlet 
control  valve  operated  by  the  large  float  in  the  mixing  box  D, 
passes  through  the  perforated  plate  B,  which  frees  it  from 
undue  agitation  into  the  measuring  chamber,  in  the  side  of 
which  is  a  long  narrow  vertical  discharge  weir  C.  It  is 

81  G 


WATER  SOFTENING  AND  TREATMENT 

obvious  that  the  level  of  the  water  in  this  chamber  bears  a 
definite  relation  to  the  amount  of  water  passing  through. 
The  weir  being  long  and  narrow,  gives  a  large  range  of  motion 
to  the  float  E,  which  rides  on  the  surface  of  the  water.  This 
float  is  counterpoised  by  a  balance  weight,  to  which  it  is 
connected  by  a  flexible  cord  passing  round  and  fixed  to  the 
motion  pulley  keyed  to  the  cross  spindle,  from  which  the 
needle  valves  G  and  G1  are  hung,  which  control  the  supply 
of  softening  reagents. 

These  needle  valves  are  carefully  calibrated,  so  as  to 
ensure  that  the  ratio  between  the  amount  of  hard  water 
discharged  by  the  weir  C,  and  the  quantity  of  reagents 
added  is  a  constant  at  all  variations  of  the  load.  The  pro- 
portions of  the  reagents,  however,  can  be  varied  to  suit 
the  nature  of  the  water,  by  adjusting  the  floats  of  the  ball 
valves,  so  as  to  increase  or  diminish  the  head  of  solution 
above  the  valve  seats. 

The  valve  G1  in  the  chamber  H1  regulates  the  supply  of 
water  to  the  lime  saturator,  from  which  it  overflows  to  the 
mixing  box  as  a  clear  saturated  solution,  whilst  the  valve  G 
in  the  chamber  H  controls  the  supply  of  soda  solution,  the 
head  of  solution  in  these  tanks  being  maintained  at  a  con- 
stant level  by  the  ball  valves,  connected  to  the  soda  tank 
and  the  main  water  inlet. 


82 


CHAPTER  X 
DETARTARIZERS 

APART  from  the  class  of  water  softeners  which  employ 
heat  and  soda  on  ordinary  softening  operations, 
there  is  a  class  of  apparatus  known  as  detartarizers,  of  which 
one  of  the  best  known  type  is  the  Chevalet  Boby  (Figs.  17, 
18).  It  consists  of  a  cylindrical  vessel  built  up  of  several 
similar  sections,  usually  five.  Each  tray  is  pierced  by 
several  pipes  or  cones,  which  dip  below  the  water  in  the  next 
lower  tray.  Steam,  preferably  exhaust,  circulates  in  the 
same  direction  as  the  water — viz.,  downwards.  Cold  water 
is  admitted  to  the  upper  part  of  the  apparatus,  steam  also 
entering  the  same  top  compartment.  Both  escape  by  the 
overflow  tuyere  to  the  tray  below,  and  this  continues  all  the 
way  down,  the  steam  being  well  mixed  with  the  water.  The 
various  trays  and  cones  adhere  to  the  lime  salts,  which 
separate  out  of  the  heated  water,  and  any  oil  not  previously 
removed  from  the  steam  goes  into  the  deposit. 

The  non-condensed  steam  escapes  from  the  lower  opening 
by  an  outlet  pipe,  and  a  float  in  the  lower  tank  regulates  the 
admission  of  the  cold  fresh  water  to  suit  the  demand. 

In  the  Delhotel  purifier  the  steam  and  water  travel  in 
contrary  directions.  In  the  Buron  purifier  water  is  fed  in  a 
shower  through  the  steam,  which  is  also  made  to  escape  by 
way  of  dip  pipes  extending  below  the  water  surface,  which 
is  kept  to  an  even  height  by  means  of  a  float  in  the  draw-off 
vessel. 

The  Granddemange  detartarizer  is  built  up  also  in  sec- 
tions like  the  Chevalet,  but  the  passage  downwards  of  steam 
and  water  is  by  way  of  the  circular  rims  of  the  various  trays 

83 


WATER  SOFTENING  AND  TREATMENT 


and  baffles  which  dip  below  the  water  level  in  the  trays. 
The  water  supply  is  regulated  by  a  float  in  the  lower  casing 
which  receives  the  water,  and  the  surplus  steam  escapes  by 
a  pipe  from  the  lower  case.  Water  and  steam  travel  in  the 
same  direction. 


INLET  OF 
EXHAUST  STEAM 


OUTLET  OF  BOILING 

DETARTARISED  WATER 

TO  FEED  PUMP 


FIG.   17.     CHEVALET-BOBY  DETARTARIZER. 


\ 


In  the  Weir  Feed  Heater  (Fig.  76)  the  water  is  sprayed 
through  steam  and  regulated  by  a  float,  and  air  or  other 
gases  which  are  held  to  be  responsible  for  so  much  corrosion 
are  trapped  off  at  the  top  of  the  apparatus. 

All  these  apparatus,  when  arranged  to  collect  deposit  on 


DETARTARIZERS 

their  trays  and  tuyeres,  are  made  so  that  they  can  be  com- 
pletely dismantled  for  cleaning  when  a  sufficient  accumula- 
tion of  scale  has  taken  place.  Such  accumulations  are  not 
difficult  to  move  when  attacked  fresh  and  wet  before  they 
have  had  time  to  dry  or  to  absorb  carbonic  acid  from  the  air. 
They  all  act  on  the  principle  that  at  100°  C.  =  212°  F.  the 
excess  of  carbonic  acid  which  keeps  lime  carbonate  in  solu- 
tion, is  given  off,  and  if  lime  sulphate  is  present  the  addition 
of  carbonate  of  soda  serves  to  convert  this  into  lime  car- 
bonate, which  deposits,  and  soluble  sodium  sulphate. 


FIG.  18.     DETAIL  OF  TRAYS.     CHEVALET-BOBY  DETARTABIZEB. 

They  find  their  chief  field  where  steam  engines  work  non- 
condensing,  or  where  there  are  no  flue  feed  heaters.  Even 
where  these  are  present  there  appear  reasons  to  consider  that 
the  detartarizer  might  be  advantageously  placed  between 
two  flue  feed  heaters,  one  of  which  should  be  fed  with  water 
at  100°  F.  from  the  condenser,  and  the  second  should  be 
fed  with  water  at  212°  F.  from  the  intermediate  detartarizer, 
which  receiving  water  at  perhaps  180°  F.  from  the  first 
heater,  would  add  sufficient  steam  to  raise  the  temperature 
to  212°  F.  for  causing  deposit,  and  so  saving  the  formation 
of  scale  in  the  second  section  of  the  flue  heater, 

85 


WATER    SOFTENING   AND    TREATMENT 

As  elsewhere  stated,  the  operation  of  water  softening  may 
be  very  varied,  and  it  must  be  arranged  to  suit  the  conditions 
of  each  particular  case. 


SECTIONAL    ELEVATION 


FIG.   19.     THE  PATERSON  FEED-WATER  HEATER  AND  PURIFIER. 

86 


DETARTARIZERS 

The  Paterson  feed-water  heater  and  purifier,  shown  in 
section  Fig.  19,  is  designed  to  utilize  exhaust  steam  for 
raising  the  temperature  of  the  feed  water.  The  steam  enters 
at  the  side  of  the  heater,  and  rises  to  the  top  through  a  series 
of  settling  and  scale-arresting  trays.  The  hard  water  is 
admitted  at  the  top  through  an  automatic  inlet  control  valve 
to  the  distributing  box,  from  which  it  passes  to  the  upper 
settling  tray,  over  the  edges  of  which  it  flows  in  a  thin  film, 
adhering  to  the  underside,  and  thence  trickling  in  a  fine  rain 
into  the  next  tray,  and  so  on  through  the  series  ;  as  a  con- 
sequence the  water  is  brought  into  intimate  contact  with  the 
exhaust  steam,  and  is  rapidly  raised  to  a  temperature  of 
212°  F.  The  carbonic  acid  gas  is  driven  off,  and  the  scale- 
forming  salts  deposited  in  and  upon  the  trays. 

After  leaving  the  trays  the  water  passes  to  the  precipi- 
tating chamber,  where  the  great  bulk  of  the  impurities  is 
deposited,  and  thence  to  the  quartz-sand  filter  bed,  where 
purification  is  completed,  and  from  which  the  boiler  feed  is 
drawn  absolutely  free  from  any  trace  of  oil  or  suspended 
matter,  and  at  a  temperature  of  from  210°  to  212°  F. 


CHAPTER  XI 
FILTERS 

ESPECIALLY  where  space  is  limited  the  complete  pre- 
cipitation of  the  lime  salts  separated  from  a  treated 
water  is  not  always  possible  by  the  method  of  settlement. 
A  certain  amount  of  the  finer  deposit  is  sometimes  carried 
forward,  and  if  it  is  desired  to  remove  this  filtration  must  be 
resorted  to. 

Filtering  material  must  be  easily  permeable  to  water  but 
of  such  a  nature  as  readily  to  pick  up  the  fine  particles  of 
deposit.  One  such  material  is  the  common  sponge  of  the 
Bahama  Islands  ;  another  is  wood-wool,  produced  from  pine 
wood,  a  material  much  used  for  packing  purposes  and  very 
cheap.  It  is  produced  by  some  process  which  leaves  it  very 
rough,  and  it  offers  therefore  an  immense  amount  of  surface 
for  catching  deposit.  Broken  coke  may  also  be  employed 
as  a  filtering  medium.  Other  filters  are  made  from  flat 
bags  of  closely  woven  cotton  canvas  held  in  frames  between 
supporting  flat  plates  of  perforated  metal. 

In  an  ordinary  filter  of  sponge  or  other  filling  it  is  con- 
venient that  the  water  should  enter  below  and  pass  upward 
through  the  material.  For  this  purpose  the  base  of  the 
filter  is  simply  a  free  space  into  which  enters  the  water.  A 
hopper  bottom  collects  sediment,  which  can  be  run  out  by 
a  sludge  tap.  The  upper  boundary  of  this  base  piece  is  a 
perforated  plate  or  a  grid  supporting  a  depth  of  a  few  feet 
of  filtering  medium  which  is  held  down  by  an  upper  plate  or 
grid.  At  the  top  is  the  outlet.  In  order  to  cleanse  such 
filters  the  course  of  the  water  is  reversed  and  the  deposit 
collected  on  the  sponge,  etc.,  is  washed  off  and  discharged 
through  the  sludge  tap.  This  type  of  filter  is  not  considered 

88 


FILTERS 

suitable  for  more  than  mechanical  filtration,  or  simply  to 
follow  up  the  action  of  depositing  chambers.  No  doubt  a 
very  cheap  filter  could  be  arranged  in  a  tall  storage  or 
depositing  vessel  by  hanging  a  grid  below  a  second  grid 
by  means  of  rods  coming  through  to  the  top  of  the  tank.  Be- 
tween the  grids  would  be  a  mass  of  wood-wool,  and  cleaning 
would  be  accomplished  by  agitating  the  material  by  raising 
and  lowering  the  lower  grid  so  as  to  cause  the  deposit  to  be 
washed  off  the  fibres,  this  being  done  when  no  water  is  pass- 
ing through  and  the  agitation  can  be  followed  by  a  period  of 
rest  for  the  deposit  to  sink  away  from  the  filter  grid.  For 
ordinary  boiler-feeding  purposes  no  serious  harm  occurs 
from  such  small  quantities  of  carbonate  of  lime  deposit  as  is 
carried  through  to  a  boiler  when  the  softening  apparatus  is 
of  ample  size.  Some  deposit  will  even  be  found  after  filtra- 
tion through  cotton  bags.  These  bags,  when  choked  with 
sediment,  can  only  be  cleaned  by  removing  them  from  their 
frames  and  washing  out  in  water,  the  bags  being  turned 
inside  out. 

For  large  supplies  of  water  a  dirty  or  muddy  source  may 
be  made  bright  and  clear  by  the  aid  of  large  sand  filters  of 
the  type  employed  by  the  water  companies.  These  filters 
consist  of  large  tanks  or  dams  with  evenly  sloped  bottoms 
on  which  are  laid  lines  of  perforated  or  open  jointed  pipes 
buried  in  a  layer  of  large  stones.  Above  this  follows  layers 
of  smaller  stuff  in  gradually  decreasing  size,  the  top  layer 
being  several  inches  of  sharp  sand.  From  the  pipes  ascend 
above  the  top  sand  a  number  of  air- vent  pipes  to  allow  the 
filter  bed  to  become  full  of  water.  Slow  downward  move- 
ment through  the  sand  is  permitted,  and  the  dirt  remains 
behind  on  the  sand,  the  surface  of  which  is  scraped  off  from 
time  to  time  as  it  becomes  choked  and  inoperative.  The 
scraped-off  sand  is  washed  for  use  again  and  again. 

This  filtration  only  removes  suspended  matter  and  bac- 
teria. It  does  not  abolish  the  necessity  for  softening,  but 
the  softening  process  may  cause  the  deposit  of  mud  carried 
in  suspension.  Occasions  will  arise  where  preliminary  filtra- 
tion may  be  an  advantage,  or  where  being  present  for  other 
reasons  may  be  utilized. 

89 


WATER  SOFTENING  AND  TREATMENT 

It  is  customary  to  allow  one  square  yard  of  filter  bed  for  each 
700  gallons  per  twenty-four  hours,  but  this  allowance  must  be 
increased  for  very  muddy  waters,  hence  the  advisability  of 
settling  ponds.  From  3  to  6  inches  per  hour  is  a  suitable 
downward  rate  of  flow  through  the  filtering  materials,  and 
9  inches  of  head  of  water  should  produce  a  sufficient  pressure 
to  do  this  when  the  filter  is  clean,  and  when  the  head  reaches 
24  or  30  inches  it  is  time  to  clean  the  surface. 

A  usual  depth  of  bed  is  6  feet,  made  up  of  30  inches  of  fine 
sand,  6  inches  of  coarse  sand,  6  inches  of  shells  and  30  inches 
of  gravel.  The  open  joint  pipe  drains  are  in  lines  every  2  to 
3  yards,  and  an  air  pipe  is  provided  for  each  9  to  16  square 
yards  of  area.  The  sand  surface  is  lightened  up  with  forks 
at  each  cleansing  to  correct  any  hard  packing. 

Where  large  quantities  of  water  are  required  and  there  is 
ample  ground  space  available,  a  settling  pond  may  with 
advantage  precede  the  filter  proper.  The  dirty  water  is 
first  pumped  into  the  settling  pond,  one  end  of  which  is 
divided  off  by  a  wall  within  which  the  pumped  water  be- 
comes quiescent.  It  escapes  thence  over  the  wall  into  the 
main  division  and  is  taken  off  preferably  from  the  surface 
at  the  extreme  end.  When  possible  a  sludging  drain  is 
provided  to  remove  accumulated  mud  or  the  tank  must  be 
periodically  emptied.  It  is  therefore  better  to  have  settling 
ponds  in  two  parts  if  the  water  carries  much  mud. 

The  settling  tank  eases  the  duty  of  the  filter.  Needless 
to  say  such  settling  tanks  may  even  be  the  sediment  tank  of 
the  actual  softening  process,  but  for  the  present  the  filtra- 
tion of  a  water  supply  is  alone  under  consideration.  A 
settling  pond  may  be  filled  by  pumping,  or  it  may  have 
direct  supply  from  a  river.  They  may  be  wholly  excavated 
in  the  ground  or  wholly  raised  above  ground.  A  very  cheap 
type  of  partly  excavated  tank  has  been  constructed  byvthe 
Author  as  follows.  First  the  foundation  of  a  brick  wall  lias 
been  dug  out  to  a  depth  of  about  3  feet  6  inches,  and  a  wide 
bed  of  good  concrete  filled  in  on  which  a  brick  wall  of  18 
inches  has  been  built  in  cement  mortar  up  to  the  ground 
level.  Above  this  the  thickness  is  reduced  to  13 J  inches. 
A  collar  joint  of  neat  cement  is  run  round  every  course.  As 

90 


FILTERS 

the  wall  rises  in  height  the  interior  of  the  tank  is  excavated 
and  the  material  tipped  and  rammed  outside  the  wall.  If 
the  calculations  are  properly  made  the  earth  excavated  will 
suffice  to  form  an  outer  flat-topped  sloped  bank  to  assist  the 
stability  of  the  brickwork.  The  concrete  foundation  being 
now  exposed  inside  the  tank  is  washed  clean  and  the  tank 
bottom  laid  in  concrete  to  join  up  to  it.  The  whole  interior 
is  rendered  in  sharp  sand  and  cement  mortar  and  finished 
smooth  with  a  finer  and  richer  coat  thinly  applied  on  a  well 
scribed  surface. 

The  outlet  or  sludge  pipe  is  placed  solidly  in  a  concrete- 
filled  trench  and  curves  up  to  finish  flush  with  the  tank 
bottom.  The  outer  earth  slopes  are  grassed  over. 

Where  a  brick  wall  must  be  depended  upon  to  retain 
water,  it  should  not  be  less  than  14  inches  thick  at  the  top, 
and  should  be  built  with  a  collar  joint  of  cement  mortar. 
The  base  thickness  should  be  at  least  two-thirds  the  height, 
to  resist  the  overturning  moment,  which  is  found  by  the 
formula  P  =  10*4  H3 ;  where  P  is  the  pressure  concentrated  at 
one- third  the  depth  of  the  water  from  the  bottom,  and  H  is 
depth  in  feet.  P  is  thus  the  overturning  moment  in  foot- 
pounds, and  should  not  exceed  one-third  of  the  stability. 
The  stability  is  the  product  of  the  weight  of  a  foot  length  of 
wall  into  the  distance  from  the  outer  toe  to  a  perpendicular 
let  fall  through  the  centre  of  gravity  of  the  section.  Thus 
in  a  pond  6  feet  deep  the  overturning  moment  is  2,246  Ib. 
If  the  wall  is  2  feet  thick  at  the  top  and  4  feet  at  the  base, 
and  battered  equally  on  each  face,  and  has  a  weight  of  150 
Ib.  per  cubic  foot,  its  stability  about  the  outer  toe  will  be 
3x150x2x6=  5,400  foot-pounds,  an  amount  that  is 
so  nearly  sufficient  that  it  would  be  made  obviously  safe  by 
reducing  the  top  to  18  inches  and  thickening  the  base  to 
4  feet  6  inches.  Sometimes  division  walls  are  built  in  the 
reservoir,  dividing  it  into  several  sections,  through  which 
the  water  flows  in  succession. 

The  graphic  method  of  determining  the  stability  of  a  wall 
is  shown  in  Fig.  20. 

Let  P  be  the  overturning  moment  =  10-4  H3  acting  at 
one- third  the  depth  of  water  from  the  bottom. 


WATER    SOFTENING    AND    TREATMENT 


Let  a  b  =  P  to  any  convenient  scale. 
Let  a  c  =  W  to  the  same  scale  as  a  b,  where  W  is  the 
weight  of  a  foot  length  of  a  wall  of  the  section  e  f  g  k. 

Then  a  c  must  be  drawn  vertically  through  the  centre  of 
gravity  of  the  figure  e  f  g  h. 

Complete  the  rectangle  abed,  and  join  a  d  cutting  the 
base  of  the  wall  at  n.  Then  h  n  must  measure  more  than 
one-third  of  h  g,  or  the  wall  will  be  of  too  low  a  stability. 
If  h  n  is  found  to  be  less  than  one-third  of  h  g,  the  wall 
section  must  be  increased  and  a  fresh  calculation  made. 
Obviously,  if  battered  on  the  outer  side,  the  centre  of  gravity 
may  be  brought  nearer  the  water  face,  and  stability  secured 

more  surely  than  by  the 
battering  of  the  inner  wall. 
It  is,  however,  to  be  re- 
membered that  a  batter 
on  the  water  face  transfers 
some  of  the  weight  of  the 
water  itself  in  a  downward 
direction  and  helps  the 
stability. 

It  is  most  important 
that  joints  in  the  brick- 
work should  be  good. 
Hence  the  advantage  of 
cement  rendering  of  the 
water  face.  Otherwise 
water  pressure  getting  in  between  joints  may  assist  to 
overturn  a  wall. 

Large  tanks  can  be  built  in  a  minimum  of  space  of  cast- 
iron  plates  bolted  together  with  internal  or  external  flanges. 
These  are  often  rendered  water-tight  by  rust  cement  joints. 
Tank  plates  with  machined  flanges  can  be  jointed  with  thin 
painted  brown  paper,  and  such  plates  with  suitable  lugs  for 
internal  stays  are  now  made  by  Mather  &  Platt  in  standard 
sizes  for  tanks  of  any  desired  size  or  shape. 

An  ordinary  sand  filter  bed  is  rectangular  in  shape  and 
about  8  feet  deep,  with  a  bottom  gently  sloped  to  a  central 
channel  covered  with  flag  or  filled  with  big  stones.  The 

92 


FIG.  20. 


FILTERS 

cross  drain  pipes  run  to  this  central  channel,  but  some  prefer 
to  cover  the  whole  bottom  with  large  stones  in  place  of  using 
pipes,  as  they  consider  the  percolation  more  even.  Others 
again  cover  the  whole  filter  bottom  with  drain  pipes  packed 
in  pebble  gravel. 

The  actual  filtering  sand  is  best  when  0-008  inches  in 
diameter,  the  limits  of  size  being  preferably  0-005  to  0-01. 
Practically  all  filtration  is  done  at  the  upper  surface,  and  it 
is  claimed  by  some  that  no  real  filtration  takes  place  until 
the  surface  has  acquired  a  sort  of  gelatinous  vegetable 
growth  over  it.  It  is  generally  agreed  that  until  this  growth 
is  formed  full-rate  filtration  should  not  be  allowed.  When 
the  filter  surface  finally  becomes  choked  by  this  growth  and 
by  mud  the  filter  is  allowed  to  run  dry,  and  the  top  layer  of 
sand  is  sliced  off  thinly,  about  J  inch  or  |  inch  only  being 
removed.  This  is  washed  and  stored  for  future  use. 
Cleansing  in  time  reduces  the  thickness  of  the  sand  to  12 
inches.  It  is  then  time  to  fill  up  the  original  with  the 
washed  sand,  the  filter  surface  being  first  thickly  sliced  off 
and  the  new  sand  well  bonded  to  the  old  by  forking. 

For  manufacturing  purposes  a  filter  may  then  usually  be 
at  once  used,  but  for  potable  purposes  a  newly  sanded  filter 
is  best  filled  up  from  below  with  previously  filtered  water, 
otherwise  the  first  water  from  a  newly  sanded  filter  must  be 
returned  to  the  top  or  run  away.  An  average  spare  area  to 
allow  for  cleaning  is  provided  to  the  extent  of  20  per  cent, 
more  or  less  according  to  conditions. 


Rapid  Filters. 

Where  space  is  an  object  filters  are  made  in  the  form  of 
closed  tanks,  and  water  is  forced  through  them  under  pres- 
sure at  rates  of  flow  upwards  of  two  or  even  three  hundred 
times  that  usual  in  ordinary  filters.  Such  mechanical  filters 
are  cleaned  by  reverse  flow  of  about  one-twentieth  the 
amount  of  water  filtered.  They  are  not  suitable  for  potable 
water  purposes,  but  only  for  manufacturing  uses. 

Large  open  sand-filter  beds  have  considerable  decolorizing 
effects  on  water.  The  Author  has  purified  the  dye-stained 

93 


WATER  SOFTENING  AND  TREATMENT 

water  of  the  River  Mersey,  black  with  dye  from  hat  works, 
by  similar  settling  ponds  and  sand  filtration. 

When  softening  is  not  to  follow  filtration  the  operation  of 
the  filter  will  be  facilitated  by  the  use  of  a  grain  or  two  grains 


Filtered 
water 


refuse 
FIG.  21.     REISERT  FILTER,  (Royle). 

of  alum  per  gallon  of  water  to  coagulate  organic  matter  and 
assist  sedimentation.  It  is  a  question  whether  such  alum 
should  not  be  added  to  the  supply  as  it  flows  into  the  settling 
pond. 

94 


FILTERS 

The  Reisert  Filter. 

In  this  apparatus  (Fig.  21)  automatic  cleansing  is  resorted 
to.  The  muddy  water  to  be  filtered  enters  the  chamber  B 
and  flows  downwards  as  shown  by  the  arrows,  into  the 
chamber  C  and  so  reaches  the  filter  bed  F,  through  which  it 
passes  leaving  behind  its  impurities  on  the  upper  surface 
of  the  filter. 

The  filtered  water  from  the  chamber  V  finds  its  way 
upwards  via  the  pipe  K  into  the  chamber  R  and  finally  over- 
flows the  diaphragm  N  into  the  filtered  water  outlet  E. 
Obviously,  the  rate  of  filtration  will  vary  with  the  state  of 
the  filter  bed  and  the  head  of  water  in  B.  As  the  filter  bed 
becomes  foul  and  its  resistance  to  the  flow  of  water  increases, 
the  water  level  in  B  rises  and  establishes  a  corresponding 
level  in  the  pipe  L,  which  it  will  be  observed  is  in  connexion 
with  C.  Inside  this  annular  pipe  L  is  another  pipe  S,  which 
extends  from  nearly  the  top  of  L  right  through  the  filter  bed 
and  receiver  V  to  the  waste  water  channel  G,  forming  the 
base  of  the  filter.  As  the  water  rises  in  L  there  presently 
arrives  a  time  when  it  overflows  at  J  and  so  forms  a  syphon. 
The  current  through  the  filter  is  thus  rapidly  reversed,  the 
water  in  R  flowing  back  through  K  and  upwards  through 
the  filter  bed,  the  deposit  on  the  filter  being  thoroughly  dis- 
turbed and  carried  into  the  waste  channel  G.  The  chamber 
R  is  proportioned  to  contain  sufficient  water  to  effect  this 
cleansing  operation  thoroughly,  and  as  this  chamber  emp- 
ties, air  enters  and  destroys  the  action  of  the  syphon  and 
the  cleansing  ceases.  The  filter  then  resumes  its  normal 
working.  This  cleansing  operation  is  repeated  as  often  as 
the  state  of  the  filter  requires  and  is  entirely  automatic. 

The  Reisert  Water  Softening  Apparatus  has  a  filter 
similarly  arranged  for  automatic  syphonic  cleansing.  Such 
filters  must  of  course  be  filled  with  a  suitable  material  of  the 
nature  of  sand,  which  will  readily  part  with  the  dirt  and 
deposit  collected  and  will  also  settle  back  when  cleaned 
into  place  for  further  action.  The  reverse  flush  also  must 
be  so  proportioned  to  the  space  occupied  that  it  will  not 
carry  away  the  filtering  material. 

95 


CHAPTER  XII 
BOILER  COMPOUNDS 

BY  far  the  most  usual  method  of  treating  boiler-feed 
water  for  prevention  of  scale  and  the  boilers  them- 
selves for  removal  of  old  scale  is  to  add  to  the  feed- water  tank 
certain  compounds.  Considerable  mystery  is  always  at- 
tached to  these  compounds,  but  there  is  nothing  really 
mysterious  in  their  composition.  Their  basis  is  soda,  and 
their  other  ingredients  are  extracts  of  tannic  substances,  and 
many  of  them  contain  starchy  or  gelatinous  matter  which 
is  supposed  to  serve  the  purpose  of  coating  each  individual 
grain  of  scale-forming  material  with  a  mucilaginous  cover, 
whose  purpose  it  is  to  prevent  the  particles  adhering.  A 
loose  mud  is  thus  formed  which  can  be  more  readily 'blown 
out. 

Where  proper  care  is  taken  to  suit  the  compound  to  the 
water  boiler  compositions  may  be  fairly  effective.  When 
the  deposition  of  additional  scale  is  prevented  by  them  and 
no  further  cementitious  action  can  take  place,  the  natural 
effect  of  working  a  boiler  is  to  set  free  scale  from  the  plates. 

The  cost  of  boiler  compounds  is  very  great  as  compared 
with  the  amount  of  active  material  present,  for  so  large  a 
proportion  of  water  is  present  in  all  compounds  of  a  liquid 
or  gelatinous  nature.  As  stated  above  most  compounds 
contain  carbonate  of  soda,  which  serves  to  reduce  the  lime 
sulphate  and  precipitate  it  as  carbonate  of  lime  in  muddy 
form.  No  doubt  also  caustic  soda  is  a  component  part  of 
some  compounds.  Indeed  it  would  be  a  very  proper  con- 
stituent where  the  compound  is  fed  into  the  feed  tank,  for 
here  we  have  an  approximation  to  that  external  treatment 


BOILER   COMPOUNDS 

of  feed  water  which  it  is  the  object  of  this  book  to  recommend 
as  the  most  correct  method  of  treatment. 

The  tannic  compounds  in  boiler  compositions  are 
extracted  from  such  timbers  as  oak,  quebracho,  chestnut, 
logwood  and  others  which  contain  tannin. 

The  object  in  employing  these  products  with  soda  is  to 
introduce  organic  matter  into  the  old  scale  in  order  that 
when  it  has  penetrated  to  the  surface  of  the  metal  below  the 
scale,  decomposition  may  be  set  up  which  causes  a  disrup- 
tive effect  and  splits  off  the  scale,  sometimes  in  large  slabs. 

The  following  reactions  are  claimed  by  M.  Taveau  to  take 
place  when  tannic  acid  produced  from  nutgalls  or  oak- 
apples  is  treated  with  water  and  subsequently  submitted  to 
prolonged  boiling. 


After  boiling  C7H6O5  =  C02+C6H603,  or  carbonic  acid 
and  pyrogallic  acid  which  forms  with  the  lime  salts, 
digallate,  gallate  and  pyrogallate  of  lime.  M.  Taveau1 
gives  a  formula  for  a  quebracho  mixture  used  by  the 
Chemins  de  fer  de  1'Ouest.  It  is  made  from  24  kilos,  of  que- 
bracho and  12  kilos,  of  caustic  soda  boiled  in  a  vessel  of  100 
litres  capacity  for  three  hours  and  made  up  finally  to  180  litres, 
which  when  cold  has  a  specific  gravity  of  11°  to  12°  Baume. 
The  liquid  is  fed  in  amounts  of  a  quarter  to  half  a  kilo,  per 
boiler  after  each  cleaning,  and  a  tenth  to  a  fifth  of  a  kilo. 
per  cubic  metre  of  subsequent  feed  water. 

The  Chemin  de  fer  du  Midi  employ  an  extract  of  que- 
bracho in  the  proportion  of  0*175  of  tannin  per  gramme  of 
lime  or  magnesia  in  1,000  litres  of  water. 

The  State  Railways  of  France  boil  130  kilos,  of  campeche 
wood  with  150  kilos,  of  carbonate  of  soda  in  1,000  litres  of 
water,  and  employ  0-0156  kilos,  of  the  liquid  per  cubic  metre 
of  water  per  degree  of  hardness. 

The  Orleans  Railways  use  a  liquid  at  8°  to  10°  Baume  pro- 
duced by  prolonged  boiling  of  60  kilos,  of  carbonate  of  soda, 
75  kilos,  of  campeche  and  25  kilos,  of  quebracho.  It  is  used 

1  Epuration  des  Eaux.     Paris  :   Gauthier  Villars. 
97  H 


WATER  SOFTENING  AND  TREATMENT 

in  the  proportion  of  0-016  kilo,  per  degree  of  hardness 
per  cubic  metre. 

The  Chemins  de  fer  de  1'Est  employ  extract  of  chestnut 
1 2  kilos . ,  carbonate  of  soda  1 0  kilos . ,  and  water  7  8  litres .  The 
chestnut  extract  has  a  gravity  of  25°  Baume,  and  contains 
40  per  cent,  of  extracts  of  which  tannin  amounts  to  three- 
fourths.  Every  day  2  litres  are  placed  in  the  water  tanks  of 
the  tender  and  4  litres  are  used  in  each  boiler  direct  after 
cleaning,  which  occurs  about  every  ten  days. 

M.  Taveau  strongly  recommends  aluminate  of  barium, 
which  has  the  disadvantage  of  high  price  enhanced  by  the 
high  atomic  weight  of  barium — viz.,  137  against  calcium  40. 
By  its  use  new  deposits  are  rendered  quite  pulverulent  and 
old  scale  is  disintegrated.  He  does  not  profess  to  explain 
these  reactions,  for  theory  does  not  explain  the  results 
which  demand  a  quantity  of  the  reagent  far  superior  to  the 
quantities  employed  successfully. 

He  suggests  that  the  reagent  becomes  successively 
regenerated,  and  is  able  to  act  again  and  again  much  as 
carbonate  of  soda  acts  on  carbonate  of  lime. 

Aluminate  of  barium  of  5°  Baume  solution  is  advised  to 
be  employed  in  doses  proportionate  to  the  degrees  of  hard- 
ness and  generally  about  10  grammes  of  the  solution  per 
degree  of  hardness  per  metre  cube  of  feed  water.  With  a 
notable  proportion  of  lime  sulphate,  %  =  10(£-A +B),  where 
A  is  the  total  hardness  in  degrees,  B  is  the  permanent  hard- 
ness, and  n  is  quantity  of  solution  in  grammes  per  cubic 
metre. 

Various  Substances. 

Of  the  many  other  substances  employed  as  disincrustants 
petroleum  has  the  credit  of  loosening  scale  from  boiler  plates 
and  of  preventing  adherence  of  fresh  deposits.  It  appears 
probable  that  the  addition  of  petroleum  in  a  dried  out  boiler 
would  ensure  the  absorption  of  the  oil  by  the  scale,  and  that 
when  under  steam  again  the  oil  would  be  driven  off  and 
produce  no  evil  effects.  Without  expressing  any  opinion 
on  the  safety  of  petroleum  the  Author  would  say  that 

98 


BOILER    COMPOUNDS 

nothing  heavier  than  the  lamp  oils  should  be  used,  for  a  heavy 
oil  which  did  not  readily  evaporate  at  the  steam  tempera- 
ture might  have  effects  as  bad  as  an  organic  oil,  though  this 
is  denied.  Experiment  seems  to  be  wanting  to  prove  the 
true  effect  of  mineral  lubricating  oils  as  compared  with 
organic  oils  in  retarding  the  passage  of  heat  from  the  plates 
to  the  water  and  in  mixing  with  lime  or  magnesia  salts  to 
form  spongy  compounds.  Caution  should  be  exercised  in 
regard  to  all  mineral  oils  pending  further  knowledge. 

VARNISHES.  —  M.  Taveau  states  that  the  adherence  of  scale 
may  be  prevented  if  the  interior  of  a  boiler  is  painted  with 
a  mixture  of  graphite  25  per  cent,  and  black  mineral  varnish 
7  5  per  cent.,  and  that  the  results  are  good  even  if  the  appli- 
cation is  inconvenient. 

He  comments  also  on  the  introduction  of  potatoes  and 
other  starchy  substances,  which  when  hydrated  become 
converted  into  cyanodextrin  and  dextrin  thus  — 


3n(C6H1005)  +nH20=raC6H1206  +  2nC6H10O5, 

and  these  combine  with  the  precipitant  salts  and  form  a 
slippery  mud  which  cannot  compact  itself  and  is  more  easily 
removed. 

No  doubt  all  the  similar  bodies  have  somewhat  these 
effects,  such  as  the  Irish  moss,  slippery  elm  bark,  etc. 

Talc  to  the  weight  of  one-tenth  the  weight  of  the  incrust- 
ing  matters  of  the  water  is  sometimes  employed,  and  though 
often  considered  inert  it  is  thought  may  give  rise  to  reactions 
akin  to  those  of  the  alkaline  silicates. 

The  promiscuous  use  of  boiler  compounds  is  not  to  be 
advised.  They  should  never  be  placed  en  masse  in  a  newly- 
cleaned  boiler,  but  should  be  thoroughly  dissolved  and  run 
in  with  the  feed.  When  the  boiler  is  set  to  work  the  com- 
pounds should  only  be  added  with  the  feed,  being  dissolved 
and  fed  to  the  feed  tank  or  pumped  into  the  feed  pipes  by  a 
small  pump  which  will  only  pump  in  the  proper  quantity  by 
working  constantly. 


99 


WATER  SOFTENING  AND  TREATMENT 

Cleaning  a  Boiler. 

Much  of  the  good  accomplished  by  a  successful  disin- 
crustant  will  be  lost  by  improper  cleaning  of  a  boiler. 

To  clean  a  boiler  properly  a  quantity  of  water  may  if 
required  be  first  blown  out  and  its  place  filled  by  a  further 
supply.  The  boiler  must  then  be  left  until  it  has  become 
cold,  the  dampers  to  the  chimney  being  a  little  open  to  cool 
the  flues,  or  if  other  boilers  are  at  work  and  this  cannot  be 
done  because  of  chilling  the  economizer,  a  current  of  air  can 
be  ensured  by  opening  up  the  back  down  take  of  a  Lanca- 
shire boiler  or  some  suitable  door  in  other  boilers. 

When  cold  the  water  should  be  run  out,  and  while  still 
wet  and  before  acted  on  by  air  the  loose  mud  should  be 
washed  off  the  whole  interior  with  a  hose  and  the  cleaners 
sent  in  at  once  to  scrape  off  the  scale  while  soft.  If  left  to 
dry,  the  deposit,  which  is  free  from  the  second  equivalent  of 
carbonic  acid,  CO2,  begins  to  absorb  this  gas  from  the  air 
and  to  form  harder  crystalline  scale. 

It  has  been  found  to  promote  scale  removal  to  supply  a 
big  dose  of  soda,  and  successively  raise  the  boiler  full  of 
water  to  212°  F.,  and  to  cool  it  twice. 

Some  years  ago  a  process  was  introduced  for  freezing 
boilers  free  from  scale.  A  boiler  thoroughly  wet  was  frozen 
by  pumping  cold  air  through  it.  The  water  in  the  scale 
disintegrated  this  by  its  expansion  when  forming  ice,  and 
caused  it  to  separate.  The  process  was  said  to  be  effectual 
and  is  based  on  sound  theory  apparently,  but  the  Author  has 
no  information  as  to  cost  or  its  present  position,  or  if  it  is  in 
practical  use. 

Scale  of  long  standing  is  apt  to  be  very  tough.  The 
Author  has  seen  the  spaces  between  the  shell  and  flue  tubes 
of  Lancashire  boilers  completely  blocked  with  scale,  and  the 
lower  back  end  of  the  shell  covered  perhaps  6  inches  thick. 
It  is  very  difficult  to  remove  such  scale  while  the  water  that 
produces  it  still  continues  to  be  employed.  Where  an 
alternative  water  supply  is  available  the  boilers  may  be 
cleansed  by  one  water  of  the  deposit  caused  by  another. 
This  is  more  readily  possible  with  locomotives.  In  one  case 

100 


BOILER    COMPOUNDS 

which  came  particularly  under  the  Author's  notice  certain 
locomotives  which  had  become  considerably  incrusted  by 
the  use  of  water  from  a  chalk  well  were  found  to  be  thor- 
oughly cleaned  when  fed  with  a  mixture  of  water  obtained 
from  a  borehole  which  collected  its  supply  from  the  sand- 
stone of  the  Upper  and  Lower  Tunbridge  Rocks  and  the 
Ashdown  Sands.  These  sand  waters  were  soft  and  had  a 
soluble  effect  on  chalk  scale. 

This  fact  brings  up  a  possible  effective  cleansing  process. 
It  has  been  suggested  that  weak  acid  will  attack  lime  scale 
before  it  will  attack  the  plates  of  a  boiler.  The  following 
effect  is  supposed  to  be  produced  by  adding  hydrochloric 
acid  to  carbonate  of  lime  scale, 

CaO,CO2  +  2HC1  =  CaClo  +  C02  +  H2O  ; 

soluble  calcium  chloride  being  produced  with  water  and 
carbonic  acid. 

Similarly  if  sulphuric  acid  is  employed  the  result  is  CaSO4, 
or  lime  sulphate,  instead  of  chloride,  and  the  scale  is  softened 
for  removal  especially  if  treated  with  a  wash  of  soda,  caustic 
or  carbonate,  to  intensify  the  breaking  up  effect.  Possibly 
even  with  a  lime  sulphate  scale  some  effect  could  be 
obtained  with  hydrochloric  acid.  The  Serpollet  tube  boiler 
is  cleaned  with  acid.  Condenser  tubes  have  been  cleaned 
by  circulating  acid  water  through  or  over  them,  and  there 
seems  no  reason  why  the  same  effect  should  not  be  secured 
with  scaled  boilers  if  the  process  is  carefully  conducted. 
Especially  after  the  proper  softening  of  a  water  has  been 
commenced  old  scale  would  be  gradually  loosened  by  aid  of 
a  very  gentle  acidulation  of  the  feed  water,  which  will  not, 
it  is  thought,  attack  the  plates  so  long  as  any  scale  remains 
on  which  the  acid  can  extend  its  energies.  Such  operations, 
of  course,  require  to  be  carried  out  under  intelligent  super- 
vision. 


101 


CHAPTER  XIII 
CORROSION 

STEAM  boilers  suffer  from  corrosion  due  to  the  solvent 
properties  of  the  feed  water. 

The  Longdendale  Water  Supply  of  the  City  of  Manchester 
comes  from  a  gathering  ground  of  the  Millstone  Grit  For- 
mation, more  or  less  clothed  with  peat  bog.  The  water 
contains  some  acid,  probably  tannic,  and  has  a  slight  cor- 
rosive effect  upon  boilers.  In  the  district  of  Mytholmroyd 
in  Yorkshire  some  of  the  streams  are  exceedingly  corrosive, 
and  will  eat  away  the  whole  inside  of  a  boiler  very  rapidly. 
The  canal  at  Walsden  fed  from  such  streams,  and  perhaps 
further  contaminated  by  acid  manufacturing  wastes,  is  also 
exceedingly  corrosive. 

Coal-pit  water  is  also  frequently  destructive  by  reason  of 
its  acidity. 

All  such  waters  can  be  neutralized  by  the  use  of  soda,  and 
should  be  neutralized  until  they  show  an  alkaline  reaction 
with  red  litmus  paper.  But  soda  is  more  expensive  than 
lime,  and  it  would  appear  more  rational  to  pass  the  feed 
water  through  a  mass  of  limestone  chippings  or  to  add  lime 
to  it  in  order  to  neutralize  the  acidity.  Should  the  neutral- 
ization be  so  complete  and  thorough  as  to  cause  scale  to  be 
deposited  in  the  boiler,  a  slight  cessation  of  the  neutralizing 
treatment  would  speedily  remove  the  scale.  Acid  water  in 
fact  only  requires  treating  on  exactly  the  same  lines  as,  when 
applied  by  Nature,  produce  the  natural  hard  waters.  Steam 
users  who  stand  aghast  at  the  Author's  suggestion  to  employ 
weak  acid  in  order  to  destroy  thick  scale  by  dissolution  will 
stand  unconcernedly  by  and  watch  the  water  from  an  acid 

102 


CORROSION 


canal  rapidly  dissolve  a  £500  boiler  to  danger  point  and 
scrap  value. 

One  pound  of  sulphuric  acid  will  destroy  one  pound  of 
carbonate  of  lime  scale.  Three-fourths  of  a  pound  of  hydro- 
chloric acid  will  produce  the  same  effect  and  hydrochloric 
acid  will  be  the  cheaper  agent  to  employ  for  boiler  cleaning 
so  long  as  its  price  is  less  than  4  as  compared  with  3  for 
sulphuric  by  weight. 

From  the  price  list  annexed,  as  given  in  a  number  of  the 
Electrical  Review,  it  will  be  seen  that  hydrochloric  acid  is 
cheaper  per  cwt.  than  sulphuric  by  about  10  per  cent.,  and 
that  as  a  destroyer  of  scale  it  is  therefore  nearly  a  third  less 
costly. 


Acid :    Hydrocliloric       .      .     <* 
,,        Nitric       .      .      .      .      . 

„        Oxalic 

„        Sulphuric       .... 
Alumina  :  Alum,  Lump,  loose 

in  casks 
„  „     Ground,  in  bags 

Sulphate  of  (14%) 
Ammonia  :  Carbonate 

„  Muriate  (crystal)    . 

»»  »»  ... 

Ammoniac  :  Sal,  Lump,   Ists  (delvd.  U.K.) 

2nds 

»>  »>          ... 

Barytes  :   Lump  Carbonate,  90-92% 

Sulphate,  No.  1,  White 
Bleaching  Powder     .... 
Borax  :  British  Refined  Crystal 
Potash  :  Bichromate  (delvd.  England) 
„       Carbonate,  90-92% 
„       Caustic,  75-80%  (c.i.f.  Hull) 

Caustic,  75-80% 
Soda  :  Ash,  Caustic,  48%,  Ordinary 

48%,  Refined 
„  Carbonated,  48% 
„         ,,  „  58%  (Ammonia  Alkali) 

net 4  10     0 

„         „      Bleachers'  Refined  Caustic  50-52% 

net         .      .      .      .      .      .      .      .        6100 

„       Caustic  White,  77%      ......     10  10     0 

„       70%      ....     net          9  12     6 

„       70o/0      .      ...       „         10  15     0 

„       60%      ....       „  8  12     6 

103 


^,    ETC.                           £       S. 

d. 

.      .      .      ..05 

0  per  cwt. 

.*....        12 

0       „ 

.      .      .      .      .        1   12 

0       „ 

......        05 

6       „ 

..'....        55 

0  per  ten 

l       ....        57 

6       „ 

.      .      .      .        5  15 

0       „ 

4  10 

0       „ 

0     0 

3fper  Ib. 

33  10 

0  per  ten 

30     0 

0       „ 

Ivd.  U.K.)       .      42     0 

0       „ 

.      .      40     0 

0       „ 

22 

0  per  cwt. 

2%        ...        3  10 

0       „ 

be     ....       2  15 

0       „ 

5     5 

0      „ 

.      .      .      .      12     0 

0  per  ten 

;land)           ..00 

3  per  Ib. 

f.  Hull)      .      .      18     0 

0  per  ten 

Hull)     .      .      .      20  10 

0       „ 

.      .      ...      24     0 

0       „ 

ary        ...       5     5 

0       „ 

ed     .      .    ..      .65 

0       „ 

.....       5  10 

0       „ 

WATER  SOFTENING  AND  TREATMENT 

Soda:  Caustic  Cream,  60%      ....        net  8  10     0  porton 

Crystals 300,, 

in  bags       .      .      .      .....  300 

„         in  barrels          376       ,, 

Bicarbonate,  in  1  cwt.  kegs          .      .      .  6  15     0       ,, 

Bichromate  (delvd.  England)         ...  0     0     2|  per  Ib. 

Silicate,  Solution,   140    Tw 4  10     0  per  ton 

Sulphate  of  Magnesia  . 4  10     0 

Talc:  (French  chalk)  c.i.f.  Liverpool  .      ...  3  10     0 

As  visible  in  steam  boilers  corrosion  takes  several  forms. 
A  very  usual  form  is  that  known  as  pitting,  which  consists  of 
isolated  circular  spots  of  active  corrosion  which  attack  the 
plates  of  the  boiler  by  no  means  generally.  This  pitting 
will  occur  internally  along  the  line  of  the  sea  tings  of  the 
Lancashire  boiler.  Pitting  is  thought  to  be  due  partly  to 
something  in  the  nature  of  the  metal  which  is  more  easily 
attacked  at  certain  spots.  It  is  recommended  that  pits 
should  be  thoroughly  scraped  clean  and  painted  with  red 
oxide  or  red  lead  paint,  and  that  further  progress  will  be 
checked.  When  very  frequent  they  become  confluent  and 
begin  to  present  more  the  appearance  of  general  corrosion. 
Pitting  is  apt  to  occur  near  the  inlet  of  cold  feed  water,  and 
much  evidence  points  to  it  being  caused  by  gases  set  free 
from  insufficiently  heated  feed,  for  pitting  will  occur  when 
scale  is  deposited  and  the  presence  of  acid  is  negatived. 

Really  acid  water  produces  general  corrosion  of  the  whole 
interior  under  water  surface  of  a  boiler.  Sometimes  the 
effect  is  so  even  and  continuous  that  no  very  accurate  esti- 
mate of  the  amount  eaten  away  can  be  made.  Sometimes 
the  shell  rivet  seams  will  hardly  be  touched,  and  in  that 
event  the  body  of  a  plate  may  be  very  seriously  corroded 
without  reducing  the  strength  of  a  boiler. 

Grooving  is  a  form  of  corrosion  which  attacks  plates  and 
angles  when  subject  to  bending,  as  at  the  line  of  contact  of 
the  front  end  plates  of  a  shell  boiler  with  the  attaching  angle 
irons,  at  the  root  of  those  angle  irons,  and  even  along  the 
longitudinal  rivet  seams  of  the  shell  of  a  lap-riveted  boiler 
and  at  the  root  curve  of  the  flanged  seams  of  the  furnace  tube 
and  round  the  base  ring  of  the  locomotive  or  vertical  boiler 
firebox. 

This  grooving  is  largely  a  mechanical  product,  but  though 

104 


CORROSION 

it  will  occur  in  neutral  water  it  is  much  intensified  by  acidity, 
and  it  is  dangerous  in  certain  situations,  as  when  it  occurs 
in  longitudinal  seams  under  tension  stress. 

Some  waters  not  naturally  acid  become  so  at  high  tem- 
peratures, as  when  chloride  of  magnesia  decomposes  with 
formation  of  free  hydrochloric  acid.  This  phenomenon  has 
become  more  serious  as  pressures  and  therefore  tempera- 
tures have  become  higher. 

Galvanic  action  has  been  advanced  as  a  cause  of  corrosion 
and  its  remedy  proposed  by  the  fixing  of  blocks  or  slabs  of 
zinc  in  metallic  connexion  with  the  boiler.  The  boiler  is 
saved  at  the  cost  of  the  zinc.  Galvanic  action,  when  ex- 
pended on  the  boiler  itself,  attacks  some  parts  more  than 
others.  Hence  the  objection  to  copper,  which  throws  the 
destructive  action  upon  the  iron,  and  hence  the  use  of  zinc 
which  is  attacked  before  iron.  Generally  the  immunity 
from  attack  depends  on  the  relative  electro-positiveness  of 
the  different  metals  involved.  Oil  and  grease  of  an  organic 
nature,  apart  from  their  dangers  in  other  respects,  will  de- 
compose to  fatty  acids  and  destroy  boiler  plates  with  the 
formation  of  iron  soaps.  The  general  fact  may  be  stated 
that  a  boiler  fed  with  hot  water  and  kept  faintly  alkaline 
will  not  suffer  from  corrosion  to  any  serious  extent,  for  the 
hot  feed  implies  freedom  from  corrosive  gases,  and  the  alka- 
linity implies  freedom  from  acid  and  galvanic  action.  Mr. 
Weir  provides  air  traps  to  remove  the  air  from  heated  feed 
and  prevent  its  entry  to  the  boiler. 

Absolutely  pure  water  may  be  assumed  to  have  an  effect 
on  a  boiler,  and  roof-collected  rain  contains  acids,  especially 
in  manufacturing  districts,  and  also  carbonic  acid.  In 
every  works  the  whole  available  roof  and  yard  area  should  be 
utilized  for  rain  collection  as  boiler  feed,  for  it  will  contain 
no  scale-forming  material. 

Boilers  are  sometimes  exposed  to  peculiar  conditions  as 
to  feed  supply. 

A  singular  case  of  explosion  occurred  in  Sheffield.  A 
boiler  using  a  river  water  exploded  from  rapid  acid  corrosion 
in  the  hands  of  new  owners,  who  treated  it  as  they  treated 
their  other  boilers  drawing  from  the  same  stream  a  few 

105 


WATER    SOFTENING    AND    TREATMENT 

yards  lower  down  stream  below  a  slight  weir.  Investigation 
disclosed  the  fact  that  the  waste  acid  from  an  electro-plating 
works  dribbled  into  the  edge  of  the  stream  a  few  yards 
higher  up  stream,  and  this  acid  flowed  directly  past  the 
intake  of  the  feed  to  the  exploded  boiler.  The  fall  over  the 
weir  thoroughly  mixed  the  acid  with  a  large  bulk  of  water, 
and  boilers  below  the  fall  were  not  affected.  The  incident 
serves  to  show  how  alert  the  engineer  must  be  to  detect 
faults.  The  new  owners  treated  the  exploded  boiler  ex- 
actly as  they  did  others  ostensibly  fed  from  the  same  source, 
though  actually  there  was  no  similarity  between  the  two 
feed  waters,  for  one  was  a  powerfully  acid  water,  the  other 
a  large  river  in  which  acid  had  been  mixed  in  small  com- 
parative quantity. 

The  water  of  the  Mersey  which  has  in  the  main  flowed 
from  the  millstone  grit  area  of  East  Lancashire  and  the 
North  Peak  district,  and  received  as  sewage  the  soft  water 
supplies  of  the  cities  and  towns  of  East  Lancashire,  is 
specially  pumped  at  Warrington  for  boiler  purposes,  or  was 
some  years  ago.  On  the  Thames  at  Deptford  the  water  is 
so  bad,  probably  because  of  chloride  of  magnesia,  that  water 
tubes  are  rapidly  corroded  through  in  holes.  The  general 
nature  of  the  water  in  any  district  may  be  judged  by  tracing 
the  river  courses  on  the  geological  maps. 

Many  boilers  fed  with  muddy  water  would  be  improved 
merely  by  provision  for  the  water  to  settle  out  its  mud,  a 
process  that  may  be  hastened  by  the  use  of  alums  and  by 
filtration. 

Every  case  requires  individual  attention,  and  there  are 
few  cases  where  an  improvement  cannot  be  made. 

In  Chapter  VI.  reference  will  be  found  to  the  corrosion 
which  takes  place  under  a  thick  sulphate  scale  such  as  occurs 
in  many  of  the  low-pressure  boilers  of  the  Burton  breweries. 


106 


CHAPTER  XIV 
INCRUSTATION  OF  PIPES 

WHEN  the  flow  of  water  through  a  pipe  is  rapid  the 
corrosion  and  incrustation  is  worse  than  with  gentle 
flow. 

Chalk  well  water  softened  by  the  lime  or  Clark's  process 
produces  a  clean  layer  of  carbonate  of  lime  inside  a  pipe. 
Hard  chalk  water  resting  in  a  pipe  and  exposed  to  heat, 
even  gentle,  may  deposit  some  of  its  lime  salt. 

Surface  waters,  especially  if  at  all  peaty,  will  produce 
rust  in  pipes.  It  is  said  that  water  from  the  Old  Red  Sand- 
stone will  neither  produce  rust  nor  deposit,  but  that  from 
the  Lower  Greensand  will  produce  rust.  It  is  often  a  more 
or  less  ferruginous  water,  and  on  exposure  to  air  its  soluble 
iron  acquires  a  further  proportion  of  oxygen,  becoming  in- 
soluble peroxide.  The  process  may  be  hastened  by  blowing 
air  through  the  water  or  by  sprinkling  the  water  through  the 
air.  The  change  is  fairly  rapid,  and  the  iron,  first  produc- 
ing cloudiness,  soon  gathers  as  a  flocculent  body  and  is 
deposited,  leaving  the  water  bright  and  clear.  Until  this  is 
complete  the  water  ought  not  to  be  passed  through  pipes, 
for  it  will  fill  them  in  process  of  time  with  an  ochreous  mass 
of  rust.  Pipes  will  not  rust  themselves  if  properly  treated 
with  Angus  Smith's  compound  of  pitch  and  tar.  Before 
treating  they  should  be  cleaned  from  end  to  end  from  each 
end  with  a  revolving  steel  brush.  They  are  then  to  be 
heated  and  dipped  vertically  into  the  melted  compound,  in 
which,  while  standing,  they  ought  to  be  again  brushed,  the 
brush  revolving  each  way,  to  remove  all  traces  of  air  bubbles, 
for  it  is  at  the  pin  holes  caused  by  air  that  rust  always 

107 


WATER  SOFTENING  AND  TREATMENT 

begins  in  a  coated  pipe.  The  Author  has  used  glass-lined 
pipes  for  particular  cases.  Galvanized  or  zinc-coated  pipes 
are  also  much  used,  but  zinc  is  by  no  means  a  permanent 
covering,  and  it  is  soluble  in  rain  water  to  some  extent,  for 
drinking  of  water  collected  on  zinc  roofs  is  a  somewhat  power- 
ful dentifuge. 

Water  containing  peaty  acids  particularly,  and  rain  water 
also,  particularly  from  town  roofs,  and  perhaps  all  soft  water, 
are  more  or  less  powerful  solvents  of  lead,  and  much  lead- 
poisoning  has  been  caused  in  the  North  of  England  by  lead 
pipes.  In  that  part  of  the  country  house-service  pipes  are 
of  lead  and  are  powerfully  dissolved,  especially  in  the  hot 
water  systems.  In  London,  where  the  water  supply  is  hard 
and  does  not  affect  lead,  the  house-service  pipes  are  of  iron. 

The  lead  solvent  action  is  curable  by  a  sufficient  dosage 
of  ground  whiting  introduced  near  the  headworks  of  the 
water  supply  so  as  to  ensure  thorough  mixture  and  solution 
before  reaching  the  houses.  If  not  thus  treated  to  prevent 
its  solvent  action,  such  water  should  only  be  served  through 
tin-lined  pipes  in  the  houses.  Probably  lead  pipes  have 
been  used  because  of  the  rusting  action  of  peat  waters  on 
iron  pipes.  When  a  water  is  safe  to  pass  through  lead  or  to 
store  in  lead  cisterns  it  will  produce  a  white-coloured  lining 
on  the  lead. 

Lead  pipes  are  rendered  safe  by  a  tinned  interior  if  this  is 
well  applied.  Iron  pipes  are  tin  lined  by  first  threading  a 
tin  pipe  through  the  iron  pipe  and  causing  the  tin  tightly  to 
expand  by  exposing  it  to  a  heavy  hydraulic  pressure. 


108 


CHAPTER  XV 
OIL  SEPARATION 

IN  order  to  render  condensed  steam  fit  for  use  in  a  boiler 
it  is  essential  to  safety  that  the  oil  it  now  contains 
should  be  removed.  Oil  separation  is  effected  both  mechan- 
ically and  chemically. 

Chemical  oil  separation  is  effected  after  the  greasy  exhaust 
steam  has  been  condensed  and  it  may  be  combined  with  a 
mechanical  process. 

Mechanical  separation  is  effected  either  before  or  after 
the  steam  has  been  condensed. 

Mechanical  separation  is  effected  more  or  less  perfectly 
by  the  De  Rycke  separator,  which  is  an  enlarged  length  of 
the  exhaust  pipe  fitted  with  spiral  blades,  designed  to  impose 
a  whirling  motion  upon  the  flowing  steam  whereby  oil  and 
water  are  thrown  outwards  by  centrifugal  action  and  drained 
off.  * 

Other  mechanical  separators  consist  of  a .  large  area  of 
sheet  metal  arranged  to  divide  the  flowing  steam  into 
numerous  thin  layers  with  the  object  of  causing  every  par- 
ticle of  oil  to  touch  such  surface  which  will  adhere  to  it. 
Such  separators  demand  large  area  and  considerable  volume 
if  they  are  to  be  successful. 

The  De  Laval  cream  separator  has  been  employed  to 
separate  oil  from  condensed  water  as  this  flows  from  the 
condenser. 

Some  modification  of  the  ordinary  separator  is  necessary 
to  provide  for  the  very  small  proportion  of  "  cream  "  —i.e. 
oil.  The  oil  discharged  from  such  a  separator  comes  off 

109 


WATER    SOFTENING    AND    TREATMENT 

clean  and  apparently  fit  for  use  again.  The  sudden  reversal 
of  flow  is  made  to  cause  oil  separation,  as  in  Holden  & 
Brooke's  Separator  (Fig.  22). 

To  avoid  grease  there  is  a  tendency  to  run  engines  without 
lubrication,  but  it  is  by  no  means  certain  that  this  practice 
can  be  of  universal  application.  When  grease  enters  a 
boiler,  no  matter  how  finely  emulsified  it. may  be,  the  condi- 
tions in  the  boiler  appear  very  effective  in  causing  the  oil  to 
separate.  The  oil  appears  to  adhere  to  the  plates  of  the 
boiler  or  to  combine  with  some  of  the  scale-forming  salts, 
especially  the  carbonate  of  magnesia  or  floury  deposit  with 
which  it  produces  a  spongy  greasy  compound  which,  if  it 
should  settle  on  any  heated  plate,  will  cause  overheating. 


FIG.  22.     HOLDEN  &  BROOKE. 


Grease  has  a  very  peculiar  effect  in  a  boiler,  for  it  retards  the 
passage  of  heat  very  seriously.  Stromeyer  says,  that  J  in. 
of  scale  will  raise  the  temperature  of  a  plate  300°  F.,  whereas 
less  than  0-001  in.  of  grease  will  produce  a  far  worse  effect. 
He  also  states  that  the  effects  of  grease  are  intensified  where 
scale  is  also  present. 

Seeing  that  grease  attaches  so  readily  to  mineral  niatter 
an  effective  method  of  clearing  water  from  the  evil  is  to  mix 
it  with  hard  water  and  put  the  whole  through  the  customary 
softening  operation,  when  the  grease  will  disappear  with  the 
sediment. 

Grease  is  essentially  dangerous,  and  no  effort  must  be 
spared  to  keep  it  out  of  boilers. 

no 


OIL    SEPARATION 


The  Hooper  Oil  Separator. 

This  apparatus,  as  made  by  Lassen  &  Hjort,  acts  on  the 
principle  of  admitting  the  greasy  exhaust  steam  into  a  vessel 
of  considerable  area.  This  reduces  the  velocity  of  flow  to  a 
minimum.  The  steam  has  then  to  pass  by  a  number  of 
perforated  plates  which  collect  the  oil  and  whence  from 
their  edges  next  the  containing  vessel  the  collected  oil  falls 
to  the  bottom  of  the  separator  and  is  drawn  off  when  the 
gauge  glass  shows  that  a  sufficient  quantity  has  collected. 


Fio.  23.     BAKER  GREASE  SEPARATOR. 


If  a  drop  pipe  can  be  brought  down  35  ft.  below  the  separator, 
it  will  be  self-draining  even  when  applied  to  the  exhaust 
of  a  condensing  engine.  Otherwise,  either  an  airlock  must 
be  provided  or  a  small  pump. 

In  the  Baker  separator  (Fig.  23)  the  principles  employed 
are  wholly  mechanical.  These  are  stated  as  follows,  and 
are  generally  applicable  to  all  mechanical  separators  of 
static  form.  They  are  : — 

in 


WATER  SOFTENING  AND  TREATMENT 

1.  Ample  capacity  to  allow  the  steam  to  expand,   and 
consequently  move  slowly. 

2.  Forced  contact  of  the  steam  with  a  surface  of  water 
which  attracts  and  holds  loose  particles  of  oil  which  have 
been  carried  forward  mechanically. 

3.  A  slight  lowering  of  the  temperature   of  the  steam, 
which  is  inevitable  where  expansion  takes  place,  and  at  the 
same   time   a    k'  dew-point "   being  reached,    at   which   the 
vapour  of  oil  begins  to  separate  itself  from  the  vapour  of 


FIG.  23A. 


water,  forming  molecules  which  adhere  to  the  first  surface 
with  which  they  are  brought  in  contact. 

4.  A  series  of  baffles  which,  dividing  the  steam  into  numfer- 
ous  thin  streams,  bring  it  into  contact  with  one  or  another 
of  these  bafflers,  which  form  at  the  same  time  channels  for 
the  grease  to  trickle  down  into  the  well  at  the  bottom  of  the 
separator,  sufficient  aggregate  area  of  steam  passages  must 
be  provided  necessary  to  avoid  undue  friction  or  back 
pressure. 

I  12 


OIL    SEPARATION 

A  considerable  saving  is  claimed  from  the  employment  of 
separators;  because  the  boilers  are  supplied  with  hot  water 
(from  the  " hot  well"  at  100°  F.)  instead  of  with  cold  water 
at  50°  F. 

The  abolition  of  grease  also  means  enhanced  safety  for 
the  boilers  and  better  results  from  the  surface  condensers, 
which  act  better  when  their  tubes  are  clean.  Then  the  oil 
can  be  filtered  and  used  again. 

When,  owing  to  the  use  of  superheated  steam  there  is  not 
much  water  in  the  exhaust  steam,  some  water  must  be 
added  to  assist  oil  separation.  The  greasy  water  discharged 
is  collected  in-  a  large  tank,  and  as  it  cools  the  oil  separates 
out  better  and  floats  and  may  be  removed  for  nitration.  In 
the  annexed  Table  VIII.  are  given  as  a  guide  a  few  dimen- 
sions of  oil  separators. 


TABLE  VIII. 

DIMENSIONS  OF  OIL  SEPARATORS. 


Approxi- 

Pounds of 
Steam 

mate 
Diameter 

Diameter                 Height 
of  Shell  of              of  Shell  of 

Face  to  Face 
of 

|  Approximate 
Weight. 

per  Hour. 

Exhaust 
Pipes. 

Separator.              Separator. 

Flanges. 

Tons.  Cwt.  Qrs. 

160 

H 

1  ft.  0  in.         1  ft.  6  in.  j     1  ft  10  in. 

023 

500 

3 

20              26             3 

0             080 

3,000 

6 

3 

0 

4 

0 

1  4 

2 

0  18     0 

7,500 

10 

4 

0 

6 

0 

5 

6 

2     3     0 

18,000 

19 

5 

3 

8 

0 

6 

9 

3     7     0 

30,000 

24 

6 

6 

9 

0 

8 

0 

630 

60,000 

'24 

8 

3 

11 

0 

1      9 

9 

9    15      0 

150,000 

36 

11 

0 

1  15 

0 

12 

,    6 

10   10     0 

Chemical  Oil  Separation. 

Complete  oil  separation  by  mechanical  means  is  not 
possible.  The  very  fine  emulsion  which  gives  a  slightly 
milky  colour  to  the  water  of  condensation  still  persists. 

In  Fig.  24  is  shown  a  magnified  image  of  a  small  film  of 
emulsified  oil.  The  oil  particles  appear  globular,  distinct 
and  independent. 


WATER    SOFTENING    AND    TREATMENT 

Fig.  24a,  however,  shows  the  same  after  treatment  with 
alumino-ferric  or  the  double  sulphate  of  iron  and  alumina. 


FIG.  24.  FIG.  24A. 

MICRO- PHOTOGRAPHS  OF  GREASY  CONDENSATION  WATER,  BEFORE  AND  AFTER 

FILTRATION. 


FIG.  25.  FIG.  26. 

ILLUSTRATIONS  OF  EXPERIMENTS  IN  THE  FILTRATION  OF  GREASY  CONDENSATION 

WATER. 

The  effect  of  this  is  to  coagulate  the  oil.     Just  what  coagula- 
tion means  is  best  shown  by  this  microscopic  enlargement. 

114 


OIL    SEPARATION 

Similarly,  Fig.  25,  No.  1,  shows  the  opacity  of  a  glassful 
of  emulsion  before  filtration.  After  filtration  through  an 
ordinary  filter  paper  no  effect  is  produced,  Fig.  25,  No.  2. 
The  same  after  treatment  with  alumino -ferric  is  seen  in 
Fig.  26,  No.  3.  The  opacity  still  continues  because  the  oil 
still  remains  in  suspension  and  stays  the  passage  of  light. 


>C»L   O.JCHABCI    SLIT 


OUTLET 

FIG.  27.     PATERSON  GREASE  SEPARATOR. 

If  this  treated  water,  however,  is  filtered,  the  effect  of  filtra- 
tion upon  coagulated  oil  is  apparent  in  Fig.  26,  No.  4.  The 
only  full  remedy  for  oil  is  chemical  treatment  and  subsequent 
filtration,  and  the  remedy  acts  best  when  combined  with  the 
make-up  water  softened  by  the  Porter-Clark  process. 

Examined  microscopically,  therefore,  jars  1  and  2  would 
show  the  appea'rance  of  the  micrograph    (Fig.   24),  while 


WATER  SOFTENING  AND  TREATMENT 

jar  3,  though  as  opaque  as  jars  1  and  2,  would  give  the 
micrograph  (Fig.  24a).  This  explains  why  it  is  thus  possible 
to  filter  out  the  coagulated  oil  and  produce  a  pure  clear 
water,  as  in  jar  4. 

Figs.  27,  28  and  29  give  the  plan  and  elevation  and  sec- 


FiLLING  UP  CONNCCTION 


FIG.  28.  PATERSON  GREASE  SEPARATOR. 

tional  elevation  of  the  Paterson  Condensation  Water  Puri^er 
for  the  purpose  of  effecting  the  results  just  described. 

It  will  be  seen  in  Fig.  27  that  the  greasy  condensation 
water,  after  passing  through  a  perforated  baffle  plate  to 
free  it  from  undue  agitation,  enters  the  measuring  float 
chamber  of  the  automatic  chemical  supply  regulating  gear, 
and  overflows  through  the  vertical  discharge  slit  or  weir, 

lib 


OIL    SEPARATION 

shown  dotted,  into  the  mixing  trough  below,  where  it  mingles 
with  the  coagulant  discharged  by  the  needle  valve  in  the 
chamber  adjacent  to  the  chemical  storage  tank,  to  which  it 
is  connected  by  a  ball  valve  for  maintaining  a  constant 
head  of  reagent  above  the  valve  seat.  The  other  valve 
chamber  may  be  connected  to  the  make-up  water  supply, 
and  adjusted  to  add  from  5  per  cent,  to  10  per  cent,  make- 
up at  this  point. 

The  bulk  of  the  grease  separates  out  on  the  surface  of  the 
water  in  the  reaction  and  precipitating  chamber  in  the  form 


FIG.  29.     PATEBSON  GREASE  SEPARATOR. 

of  a  thick  sludge,  which  can  be  overflowed  to  waste  when 
necessary.  The  sedimentary  matter  falls  to  the  bottom 
and  is  flushed  to  the  drain  periodically.  The  water  is  par- 
tially clarified  before  passing  into  the  filter  by  upward 
straining  through  wood-wool  fibre,  contained  in  the  pre- 
liminary strainer. 

The  filtering  medium  employed  is  a  special  quartz  silver 
sand  (almost  pure  silica)  resting  upon  a  bed  of  fine  pea  gravel. 
The  action  of  the  coagulant  is  to  form  an  exceedingly  fine 
gelatinous  precipitate,  which  seals  up  the  interstices  between 

117 


WATER  SOFTENING  AND  TREATMENT 

the  sand  grains  and  forms  an  impervious  barrier  to  the  oily 
globules.  The  pure  water  is  drawn  off  uniformly  from  the 
under  side  of  the  bed  through  a  large  number  of  gun-metal 
strainers,  screwed  into  the  manifold  pipe  system  leading  to 
the  pure  water  outlet  duct.  These  strainers  are  fitted  with 
finely  perforated  renewable  phosphorbronze  screens.  An 
automatic  outlet  controller,  by  throttling  the  outlet  dis- 
charge, prevents  the  possibility  of  the  filter  being  drained 
empty  when  running  on  light  load. 

To  wash  the  filter  the  current  of  water  is  reversed  through 
the  bed  and  the  impurities  flushed  over  the  waste  gutter  to 
the  drain.  This  cleansing  is  assisted  by  the  agitation, 
aeration,  and  sterilization  obtained  from  forcing  air  through 
the  bed  by  means  of  an  air  injector.  Attention  is  required 
about  ten  minutes  daily  for  re-charging  the  chemical  storage 
tank  and  flushing  out  the  filter.  In  electric  lighting  stations 
during  the  summer  when  the  load  is  light,  the  purifier  may 
only  require  attention  once  a  week 


118 


CHAPTER  XVI 
MECHANICAL  BOILER  CLEANERS 

THERE  is  a  class  of  apparatus  known  as  mechanical 
boiler  cleaners,  which  depend  for  their  effect  on  the 
fact  that  freshly  separated  lime  and  magnesia  salts  are  often 
very  fine  and  light  and  float  at  the  surface.     These  boiler 


FIG.  30.     THE  HOTCHKISS  APPABATUS. 
119 


WATER    SOFTENING    AND    TREATMENT 

cleaners  consist  of  a  vessel  placed  above  the  boiler  and  con- 
nected with  it  by  two  pipes,  one  of  which  ascends  from  a 
skimming  funnel  placed  at  the  water  surface,  while  the 
other  descends  well  below  water  level.  It  is  found  that  a 
continuous  circulation  of  water  is  maintained  by  reason  of 
the  fact  that  water  in  the  rising  pipe  tends  to  form  more 
or  less  foam  as  it  attains  a  higher  level  and  is  under  less 
pressure,  whereas  the  descending  column,  entering  upon 
horizons  of  greater  pressure,  is  maintained  as  water.  The 
upper  vessel  is  divided  by  a  diaphragm  plate  and  the  cir- 
culating water  drops  its  sediment  in  the  quiet  vessel,  whence 
it  is  blown  out.  In  some  cases  the  effect  has  been  such  that 
boilers  have  only  required  cleaning  at  long  intervals.  All 
the  water  appears  to  circulate  through  the  cleaner  or,  at 
least,  all  the  surface  water  carrying  the  new  scale-forming 
matter.  Only  temporary  hardness  can  be  dealt  with,  any 
sulphate  requires  the  help  of  soda  in  addition  so  as  to  con- 
vert the  sulphate  of  lime  to  the  carbonate  which  is  then 
within  the  capacity  of  the  cleaner  to  deal  with. 

The  Hotchkiss  apparatus  (Fig.  30)  is  based  on  the  above 
principles,  and  it  is  claimed  to  be  effective,  not  only  as  a 
remover  of  the  lime  salts,  but  also  of  grease  and  oil,  so  that 
condensed  greasy  steam  may  be  used  in  the  boiler  without 
danger.  The  economy  of  these  apparatus  lies  in  the  fact 
that  blowing-out  ceases  to  be  necessary  and  much  heat  is 
thus  saved. 


120 


A 


CHAPTER  XVII 
PURE  WATER 
USUAL  standard  of  purity  for  water  is — 


Hardness  below  6°. 

Chlorine  not  above  1  in  100,000  if  of  organic  origin. 
Nitrites  and  nitrates — indicative  of  previous  sewage  contamina- 
tion, 0-2  to  0-3  parts  per  100,000. 
Ammonia  salts  not  above  0'099  per  100,000. 
Organic  carbon,  not  over  2  per  100,000. 
Organic  nitrogen,  not  over  3  per  100,000. 
Albumenoid  ammonia,  not  above  0-0099  per  100,000. 

Schomberg  advises  that  a  water  may  be  made  chemically 
pure  by  adding  to  each  litre  of  water  0-06  gramme  of  free 
bromine  in  the  form  of  potassium  bromide.  Very  polluted 
water  requires  more  and  may  be  made  slightly  straw  colour. 
In  five  minutes  all  injurious  germs  will  be  destroyed,  and  in 
another  five  minutes  the  addition  of  an  equal  amount  of 
9  per  cent,  ammonia  solution  will  render  the  water  clean 
and  tasteless  and  fit  to  drink. 

The  addition  of  a  minute  fraction  of  sulphate  of  copper 
to  water  is  said  efficiently  to  destroy  all  bacterial  life. 

Pure  water  in  the  above  senses  is,  however,  not  required 
for  steam-boiler  purposes  and  lies  outside  the  scope  of  this 
volume,  which  deals  with  the  reduction  of  deposit,  for,  both 
in  steam  raising  and  in  manufacturing,  the  absence  of  deposit 
is  conducive  to  efficiency  in  steam  generation  and  good 
quality  in  the  texture  or  colour,  or  both,  of  tanned  goods, 
dyed  goods  or  bleached  fabrics.  Rather  than  use  any 
chemicals  which  will  leave  salts  in  solution  in  a  boiler,  such 
as  sulphate  of  soda,  when  sulphate  of  lime  is  reduced  by 
carbonate  of  soda,  brewers  will  allow  their  boilers  to  become 

121 


WATER  SOFTENING  AND  TREATMENT 

badly  incrusted.  Any  salt  in  solution  will,  of  course,  pass 
over  to  the  vats  with  the  priming  water.  Experiment 
should  show  whether  the  usual  steam  dryers  or  water  sepa- 
rators would  not  fully  cure  this.  Dry  steam  will  not  carry 
salts.  The  Author  hesitates  to  say  if  every  particle  of  salt 
can  be  removed  by  a  water  separator  and  cannot  say  how 
small  a  proportion  of  sulphate  of  soda  could  be  permitted 
in  brewing.  This  point,  however,  is  properly  within  the 
duty  of  the  brewery  chemist  to  consider,  for  if  drying  can 
be  brought  to  a  sufficient  perfection  it  should  pay  well  in 
fuel  saved  to  put  a  stop  to  the  very  severe  scaling  which  is 
found  to  occur  in  brewery  low-pressure  boilers  using  hard 
water. 

The  Author  suggests  that,  low-pressure  boilers  are  a  mis- 
take. The  velocity  of  steam  inside  a  boiler  and  through 
the  outlet  pipes  is  inversely  as  the  absolute  pressure,  and 
priming  is  thus  apt  to  be  more  severe  with  low-pressure 
boilers.  When  particularly  pure  steam  is  wanted  the  anti- 
priming  pipes1  in  a  boiler  should  be  long  and  finely  perfo- 
rated, and  even  two  outlet  valves  may  be  an  advantage. 

Pure  water  may  be  produced  by  the  circulation  of  steam 
from  a  high-pressure  boiler  through  the  tubes  of  an  evapo- 
rator. Low  pressure  steam  may  thus  be  raised  from  a  scale 
forming  water  and  the  scale  which  forms  on  the  evaporator 
coils  can  readily  be  removed.  Unless  sulphate  of  lime  is 
present,  needing  soda  to  remove  it,  a  water  can  be  softened 
by  lime  without  fear  of  the  effects  in  brewing. 

1  See  Steam  Pipes  :  their  Design  and  Construction  (Constable 
&  Co.). 


122 


Appendix   No. 


ABSTRACT  OF  REPORT  UPON  THE  INCRUSTATION  IN 

BOILERS, 

OCCASIONED  BY  THE  ACTION  OF  SOME  OF  THE  WATERS  IN  AND 
AROUND  MANCHESTER  AND  THE  NEIGHBOURHOOD. 

BY 
DR.  R.  ANGUS  SMITH,  F.R.S.,  F.C.S.,  ETC.,  ETC. 

PART  FIRST. 
CHALK  AND  GYPSUM  WATERS. 

THE  specimens  sent  to  me  to  represent  the  waters  of  this 
district  were  of  three  kinds — 1st,  Alkaline  or  rather  Chalk 
Water  ;  2nd,  Neutral  or  Gypsum  Water  ;  and  3rd,  Acid  Water. 
The  second  is  always  in  this  district  found  mixed  with  No.  1 
or  3.  1  and  3  are  always  mixed  up  with  No.  2.  Nos.  1  and  3 
cannot  occur  in  one  specimen. 

It  is  of  course  weh1  known  that  all  such  waters  are  hurtful 
to  boilers,  but  in  very  different  ways.  The  first  is  hurtful  be- 
cause on  being  warmed  the  carbonic  acid  which  keeps  the  lime 
in  solution  is  driven  off  with  the  vapour  of  the  water,  and  the 
carbonate  of  lime  falls  to  the  bottom  in  form  of  a  crust  more  or 
less  compact.  This  crust  is  a  well  known  substance  and  is  the 
source  of  many  complaints,  and  the  cause,  no  doubt,  of  many 
accidents  and  injuries. 

As  an  example  of  crust  from  water  belonging  chiefly  to  the  red 
sandstone,  a  specimen  from  Tyldesley  and  one  from  near  Man- 
chester were  analysed,  giving — 
1.  From  Tyldesley  :— 

Carbonate  of  lime    ....     83*995  per  cent. 
Sulphate  of  lime       .      .      .      .       3-625        „ 
Carbonate  of  magnesia        .      .  .     8-833        „ 

Silica 3-000 

Oxide  of  iron  and  alumina      .       0*500 


99*953 
123 


WATER    SOFTENING    AND  TREATMENT 

2.  From  Manchester  :— 

Carbonate  of  lime  with  oxide  of 

iron    .       .       .      .      .      .      .  70-108  per  cent. 

Sulphate  of  lime       ....  3-220 

Carbonate  of  magnesia        .      .  21*876        ,, 

Silica   .      .      .      .      .     '.      ..  4-795 


99-999 

Many  attempts  have  been  made  to  remove  the  crust  without 
the  use  of  the  hammer,  and  many  attempts  have  also  been  made 
to  prevent  its  formation.  The  necessity  of  removing  it  by 
force  occurs  at  intervals  of  days,  weeks,  or  months,  according  to 
the  amount  of  lime  in  the  water  and  the  amount  of  water 
evaporated.  This  mechanical  method  of  removal  must  certainly 
be  injurious  to  the  boilers.  Not  to  mention  the  great  amount 
of  vibration  to  which  they  are  exposed  by  the  process  of  ham- 
mering, a  certain  amount  of  oxide  of  iron  is  always  removed 
by  each  removal  of  crust.  This,  of  course,  is  soon  succeeded 
by  another  coating,  and  the  process  of  rusting  is  thereby  facili- 
tated. 

To  prevent  the  formation  of  the  crust,  it  has  been  proposed 
to  coat  each  particle  of  lime  at  the  moment  of  its  escape  from 
solution  with  an  organic  substance,  such  as  starch  or  mucilage, 
or  any  cheap  material  soluble  to  some  extent  in  water.  Such 
substances  have  been  found  in  potatoes,  buttermilk,  gelatine, 
fish,  blood,  and  oily  or  waste  oleaginous  matter,  and  we  may 
add  all  the  soluble  parts  of  plants.  When  the  carbonic  acid 
leaves  the  water,  the  particles  of  carbonate  of  lime  which  are 
then  allowed  to  fall  cannot  approach  so  closely  to  each  other 
as  in  pure  water,  and  instead  of  uniting  into  a  compact  body, 
they  remain  in  a  separate  condition  and  form  with  the  water  a 
mass  of  mud.  This  mud  is  blown  off  from  the  boiler  at  given 
intervals,  according  to  the  circumstances  of  the  case. 

These  methods  are  generally  found  sufficient  for  a  short  time, 
but  seldom  for  a  long  one. 

A  cleaner  and  much  more  beautiful  method  was  proposed 
some  years  ago.  It  consisted  in  the  use  of  chloride  of  ammonium 
or  sal-ammoniac.  When  this  salt  is  boiled  with  carbonate  cf 
lime,  the  chlorine  unites  with  the  calcium  and  forms  chloride 
of  calcium,  which  is  very  soluble  in  water  ;  the  ammonia  goes 
with  the  carbonic  acid  into  vapour.  I  am  told  that  the  process 
is,  or  at  least  has  been,  used  a  good  deal  on  the  railways  in  the 
South  of  England,  where  the  water  contains  carbonates  of  lime 
and  magnesia,  with  frequently  no  more  than  a  small  trace  of 
any  other  salt.  Sal-ammoniac  costs  about  £35  a  ton.  A  ton 
will  serve  for  about  a  million  gallons  of  the  water  of  the  Thames. 

124 


APPENDIX 

When  muriate  of  ammonia  or  sal-ammoniac  is  boiled  in  solution 
in  water,  some  ammonia  is  given  off  and  the  acid  remains.  This 
acid  (muriatic)  dissolves  iron  unless  a  large  amount  of  lime  be 
present.  The  boilers  are,  of  course,  attacked  by  an  excess  of  it. 
It  is  probable  also  that  the  ammonia  or  carbonate  of  ammonia 
given  off  in  this  process  may  come  into  contact  with  brass  or 
copper,  to  which  it  is  apt  to  be  injurious. 

When  water,  such  as  the  first  class  or  chalk  water,  is  to  be 
treated,  the  process  of  Professor  Clark  is  by  far  the  best.  This 
process  consists  in  adding  caustic  lime  to  precipitate  the  car- 
bonate of  lime  or  chalk.  But  neither  of  these  processes  fits 
well  the  waters  of  this  district.  Clark's  process  has  not  been 
found  convenient  for  waters  containing  only  5  or  6  grains  of 
carbonate  of  lime,  although  with  great  care  it  may  be  made  to 
apply  to  them.  Neither  Clark's  process  nor  the  sal-ammoniac 
process  has  any  effect  on  the  sulphate  of  lime  contained  in  water. 

The  waters  around  Manchester  may  be  considered  as  repre- 
sented by  the  following  analysis,  which  represents  no  one 
specimen  in  particular — although  nearly  that  of  the  old  water 
supply,  [i.e.  prior  to  Longdendale.  W.H.B.] 

Carbonate  of  lime,  6  grains  per  gallon  ; 

Sulphate  of  lime,  8  grains  per  gallon  ; 

Carbonate  of  magnesia,   1  to  2  or  3  grains  per  gallon. 

By  Clark's  beautiful  process,  28  grains  of  caustic  lime  throw 
down  50  grains  of  carbonate  of  lime  from  the  water,  and  become 
themselves  converted  into  other  50  grains  of  carbonate  of  lime. 
By  this  means  28  grains  of  caustic  lime  thrown  into  a  solution 
of  carbonate  of  lime  in  water  cause  the  precipitation  of  100 
grains  of  that  salt.  The  lime  when  it  exists  in  solution  in  water 
is  made,  properly  speaking,  a  bi-carbonate,  as,  besides  water  to 
keep  it  in  solution,  there  is  also  carbonic  acid.  The  precipitate 
falls  down  white  and  like  fine  chalk,  which  it  really  is.  If  there 
be  organic  matter  existing  in  the  water  the  lime  attaches  itself 
to  a  large  proportion  of  it,  and  the  precipitate  is  thereby  darker 
according  to  the  amount  of  impurity,  whilst  the  water  is  pro- 
portionately clear.  This  plan  throws  down,  in  many  cases, 
also  as  much  of  the  magnesia  as  may  be  in  a  state  of  carbonate. 
The  sal-ammoniac  process  acts  also  on  the  carbonate  of  magnesia. 
It  might  be  said  that  even  with  such  waters  as  we  have  near 
Manchester  this  plan  could  be  adopted,  if  great  care  were  to 
be  taken  to  remove  the  carbonate  of  lime  ;  the  sulphate  remain- 
ing, being  soluble,  would  not  form  a  crust,  if  it  were  blown  off 
before  the  solution  became  extremely  concentrated.  I  will  not 
say  that  this  is  impracticable,  but  it  seems  to  require  more 
refinement  than  we  can  expect,  as  I  have  just  been  presented 

125 


WATER  SOFTENING  AND  TREATMENT 

with  a  specimen  of  crust  of  extreme  hardness,  which,  on  analysis, 
gives  78' 16  per  cent,  of  sulphate  of  lime. 

The  existence  of  this  crust  is  of  itself  a  sufficient  proof 
of  the  great  importance  of  removing  the  sulphate  of  lime  as  well 
as  the  carbonate.  The  crust  made  by  the  former  is  generally 
harder  and  more  difficult  to  remove,  whilst  it  is  scarcely  possible 
to  affect  it  by  any  chemical  method.  At  the  same  time  it 
must  be  added  that  there  are  waters  in  Lancashire  to  which 
this  process  of  Professor  Clark's  can  most  readily  be  applied, 
such  as  some  from  parts  of  the  red  sandstone,  and  contain 
12  to  15  grains  of  carbonate  of  lime  per  gallon,  with  very  little 
sulphate.  The  necessity  of  overcoming  the  difficulty  presented 
by  the  sulphate  of  lime  induced  me  to  make  many  trials  ;  the 
results  of  the  most  practicable  will  be  here  given.  It  is  known 
that  carbonate  of  soda  throws  down  the  lime  from  sulphate  of 
lime,  or  rather  decomposes  the  salt.  If  we  add  carbonate  of 
soda  to  a  water  containing  sulphate  of  lime  or  gypsum,  carbonate 
of  lime  falls  down,  and  sulphate  of  soda  remains  in  solution. 
Now,  sulphate  of  soda  is  an  extremely  soluble  salt,  it  is  extremely 
innocent,  and  would  rarely  require  blowing  off. 

By  two  processes,  then,  the  whole  of  the  lime  may  be  removed 
from  the  water.  One  process  by  caustic  lime  removes  the 
carbonate,  and  another  process  by  carbonate  of  soda  removes 
the  sulphate.  As  it  is  found  that  a  small  amount  of  carbonate 
of  lime  does  not  precipitate  well,  this  additional  quantity 
derived  from  the  sulphate  will  assist  it  in  rapidly  falling. 

It  is  not  agreeable  to  render  anything  complicated,  and  one 
process  has  already  been  found  too  much.  By  a  little  considera- 
tion we  can  convert  these  two  processes  into  one. 

Caustic  soda,  when  added  to  a  solution  of  carbonate  of  lime 
in  water,  or  a  solution  of  bi-carbonate  of  lime,  takes  up  the 
carbonic  acid  exactly  in  the  same  manner  as  caustic  lime,  and 
precipitates  carbonates.  (This  is  similar  to  Clark's  process,  but 
so  far  is  inferior  that  the  caustic  soda  will  not  itself  fall  out  of 
the  water.)  In  doing  this  the  caustic  soda  becomes  carbonate 
of  soda,  which,  as  we  have  seen,  decomposes  sulphate  of  lime. 
Now,  if  we  add  caustic  lime  to  carbonate  of  soda,  we  obtain 
caustic  soda.  By  the  use  of  caustic  soda,  then,  we  unite  the 
two  processes  into  one.  Again,  as  caustic  soda  is  formed  by 
the  mixture  of  lime  and  carbonate  of  soda,  we  may  use  thefci 
together  for  precipitation,  or  we  can  make  the  caustic  soda 
separately  and  then  use  it.  When  rapid  precipitation  is  wanted 
the  lime  and  carbonate  of  soda  are  best  used  together  ;  when  a 
large  precipitate  is  to  be  avoided,  then  it  is  better  to  use  the 
caustic  soda  alone. 

Carbonate  of  soda  and  lime  are  equivalent  to  caustic  soda  used 
alone.  31  grains  of  dry  caustic  soda  will  throw  out  of  solution 

126 


APPENDIX 

50  grains  of  carbonate  of  lime.  28  grains  of  lime  do  the  same, 
but  they  fall  down  also  and  make  the  precipitate  100  of  carbonate 
of  lime.  Soda,  therefore,  causes  a  less  bulky  precipitate  than 
lime  when  chalk  alone  is  to  be  treated  in  the  water,  because  the 
soda,  instead  of  falling  like  the  lime,  remains  in  the  solution. 
But  now  comes  the  chief  difference.  When  the  caustic  soda 
has  removed  the  carbonate  of  lime,  it  becomes  converted  into 
carbonate  of  soda,  and  this  carbonate  of  soda  acts  upon  the 
sulphate  of  lime,  forming  carbonate  of  lime  again  and  sulphate 
of  soda.  The  whole  of  the  lime,  therefore,  falls  in  whatever 
condition  it  be,  and  a  little  sulphate  of  soda  only  remains.  The 
salts  in  the  water  are  composed  thus  :— 

Lime     .    -  *      .      .      .    Carbonic  acid. 
Carbonic  acid. 
Lime     .      .      .      .      .     Sulphuric  acid. 

Add  caustic  soda  and  we  have  — 

Lime  .....  Carbonic  acid. 
Soda  .....  Carbonic  acid. 
Lime  .....  Sulphuric  acid. 

Which  again  breaks  up  into  — 

•t  Soda     .      .      .      .      .     Sulphuric  acid,  or  sulphate  of  scda. 
Lime    .....      Carbonic  acid,  ) 
Lime    .....      Carbonic  acid  J  or  carbonate  of  lime. 

These  two  latter  portions  of  carbonate  of  lime  fall  together,  and 
the  sulphate  of  soda  remains. 

As  many  persons  who  read  this  will  not  understand  chemical 
symbols,  I  have  used  the  full  words  ;  chemists  can  easily  translate 
it  into  their  formulas.  It  might  be  shortly  written  so  — 

CaO  2CO2  +  CaO  SO,  +  NaO  =  CaOCO2  +  NaO  CO,  + 


CaO  SO3  =  NaO  SO3  +  2CaO 

Carbonate  of  magnesia  and  sulphate  form  similar  compounds 
and  undergo  the  same  decompositions,  according  to  circumstances 
to  be  noticed.  Let  us  apply  the  decomposition  to  the  normal  water 
around  us  containing  6  grains  of  carbonate  of  lime  dissolved  in 
carbonic  acid  and  water,  and  let  us  suppose  8*16  grains  of  sulphate 
of  lime.  Add  3*  72  grains  of  caustic  soda  ;  these  at  once  become 
6-36  grains  of  carbonate  of  soda,  and  6  grains  of  carbonate  of 
lime  fall.  The  6'36  grains  of  carbonate  of  soda  attack  the  8*16 
grains  of  sulphate  of  lime  and  become  8-52  of  sulphate  of  soda, 
whilst  other  6  grains  of  carbonate  of  lime  fall.  Altogether  there 

1  In  the  present  day  notation  for  Na  read  Na2  in  each  case.  The 
present  atomic  weight  of  Na  is  23  to  oxygen  =  16.  —  AUTHOR. 

127 


WATER  SOFTENING  AND  TREATMENT 

are  12  grains  thrown  down,  and  the  soda  is  made  to  act  twice 
decomposing  the  salts.  The  first  action  is  by  absorbing  an  acid  ; 
the  second  is  by  changing  this  acid  for  another.  Used  in  this 
manner  31  grains  of  caustic  soda  throw  down  100  grains  of 
carbonate  of  lime. 

If  any  one  will  say  that  the  soda  goes  to  the  sulphuric  acid 
at  once,  and  not  in  the  method  I  have  pointed  out,  I  shall  only 
add  that  the  result  will  be  exactly  the  same. 

If  grains  are  not  found  agreeable  as  units,  it  is,  of  course, 
easy  to  make  the  calculations  on  a  larger  scale.  If  we  use 
7,000  gallons  of  water,  our  numbers  will  remain  the  same,  pounds 
taking  the  place  of  grains. 

7,000  gallons  of  water,  such  as  mentioned,  contain — 
6  Ibs.  of  carbonate  of  lime, 
8' 16  Ibs.  of  sulphate  of  lime, 
add  3*72  Ibs.  of  caustic  soda, 
the  result  is    8*52  Ibs.  of  sulphate  of  soda  in  solution. 

and  12  Ibs.  of  carbonate  of  lime  thrown  down. 
Thus,  as  before,  28  Ibs.  of  lime  remove  50  of  carbonate  of  lime 

from  chalk  waters. 

31  Ibs.  of  soda  remove  100  of  carbonate  of  lime 
from  mixed  waters  such  as  this. 

Soda,  therefore,  removes  nearly  double  the  quantity  removed 
by  lime,  in  the  case  of  mixed  chalk  and  gypsum  waters,  but 
the  price  is  about  20  times  greater  than  that  of  lime.  The 
process  will,  therefore,  be  10  times  more  expensive  than  the 
lime  process.  It  is,  however,  scarcely  fair  to  compare  the  two, 
as  the  lime  process  will  not  answer  the  purpose  in  view.  Let 
a  ton  of  carbonate  of  soda  cost  £10,  the  caustic  soda  in  it  and 
the  lime  used  would  cost  about  £18.  The  calculation  of  20 
times  is,  therefore,  rather  low.  However,  a  ton  of  soda  costing 
about  £18  would  precipitate  2,107,527  gallons  of  water,  with  12 
grains  of  carbonate  of  lime  in  solution,  or  4,215,054  of  mixed 
water,  such  as  we  have  in  view. 

It  may  be  asked,  in  what  way  the  precipitant  should  be  used. 
I  believe  the  best  of  all  methods  is  to  have  a  tank  for  precipitation, 
and  when  the  clear  water  remains  after  the  fall  of  the  lime,  it 
may  be  transferred  to  the  boiler.  As  the  precipitation  occurs 
very  rapidly,  it  would  not  be  needful  to  have  more  than  a  day's 
supply  of  prepared  water.  I  believe  that,  in  many  cases,  a  few 
hours'  supply  would  be  enough.  According  to  experiments 
made  to  try  Professor  Clark's  process,  six  hours'  supply,  or  even 
less,  would  be  enough. 

Caustic  soda  is  made  by  adding  slaked  lime  to  carbonate  of 
soda. 

128 


APPENDIX 


1  ton  of  caustic  soda  (dry)  is  made  by 


112  Ibs. 

1  Ib.  or  7,000  grains 


Carbonate  of  soda.         Caustic  lime. 
3829-6  Ibs.  andl  2023  Ibs. 
=  34- 19  cwt.    „       18-06  cwt. 
or  34  cwt.  21  Ibs. 
191  Ibs.          and  101-15  Ibs. 
11967-7  grains  „  6322-1  grains, 
or  27-36  ounces  or  14-4  ounces. 


To  prepare  caustic  soda  the  carbonate  of  soda  is,  of  course, 
used  in  solution.  It  is  better  warmed,  but  this  is  not  needful  ; 
the  warmth  of  newly-slaked  lime  assists  the  action.  As  it  is  not 
possible  to  weigh  the  caustic  soda  dry,  and  not  convenient  to 
weigh  it  in  any  condition,  I  shall  make  the  calculations  on  the 
amount  of  carbonate  converted  into  caustic. 


Amount  of  carbonate  of  soda  to  be 

converted  into  caustic  and  used  for 

1,000  gallons  of  the  water  to  be  treated. 

Supposing  1  gr.  carbonate  lime  to  exist 

hi  solution  in  a  gall,  water  1060  grains. 

2  grains     „  2120 

3  „  „  3180 

4  „  „  4240 

5  „  „  5300 

6  „  „  6360 

and  so  on.  This  is  equal  to  2'42  ounces  of  carbonate  of  soda 
for  1,000  gallons  of  water  for  every  grain  of  carbonate  of  lime 
per  gallon.  This  will  also  precipitate  the  lime  from  the  sulphate 
at  the  rate  of  8 '16  grams  of  sulphate  for  every  six  grains  of 
carbonate. 

If  sulphate  of  lime  should  exist  in  the  water  alone,  the 
carbonate  of  soda  may  be  used  by  itself  without  adding  lime 
to  reduce  it  to  caustic  soda,  although  it  is  better  to  add  a  minute 
quantity  of  caustic  soda  in  order  to  remove  the  small  amount 
of  carbonic  acid  dissolved  even  in  such  waters.  In  this  case 
the  amounts  used  will  be — 


Carbonate  of  soda  for  1,000  gallons. 

For  1  grain  of  sulphate  of  lime  in  a  gallon  of  water,  use  .     779-4grns- 
2  grains 
3' 

4 


1558-8 
2338-2 
3117-6 
3897-0 
4676-4 
5455-8 
6235-2 


This  is   equal  to   T78  ounce  of   carbonate   of  soda  per   1,000 
gallons  for  each  grain  of  sulphate  of  lime  per  gallon. 

129  K 


WATER  SOFTENING  AND  TREATMENT 

For  salts  of  magnesia  : — 

Carbonate  of  soda  made  caustic  and 
added  to  1,000  gallons  of  water. 

For  1  grain  of  carbonate  of  magnesia  in  a  gallon,  use  .  .    1261*9  grns. 
„    2  grains  „  „  „    .  .    2523-8     „ 

„    3     „  „  „  „    ..    3785-7     „ 

This  is  equal  to  2'88  ounces  of  soda  per  1,000  gallons  for  each 
grain  per  gallon. 

For  sulphate  of  magnesia  existing  where  there  are  no  carbonates 
the  amounts  are  as  follow — 

Grains  of  carbonate  of  soda  reduced  to  caustic 
and  added  to  1,000  gallons  of  water. 

For  1  grain  of  sulphate  of  magnesia  per  gallon,  use    ...      883-33  grns. 
„    2  grains  „  „  „     ...    1766-60     „ 

„    3     „  „  „  „     ...    2649-90     „ 

This  is  equal  to  2-01  ounces  of  carbonate  of  soda  per  1,000 
gallons  for  each  grain  of  sulphate  of  magnesia  per  gallon. 

It  is  not  needful  to  add  any  soda  to  precipitate  the  sulphate 
of  lime  or  magnesia  unless  existing  in  a  greater  proportion  than 
8-16  of  sulphate  of  lime  to  6-0  of  carbonate. 

There  are  cases  where  special  calculations  must  be  made  ; 
for  example,  where  there  are  mixtures  of  carbonates  and  sul- 
phates of  lime  and  magnesia,  but  I  fear  to  complicate  the  matter. 

The  precipitation  by  caustic  soda  is  not  exactly  a  novelty, 
but  I  have  not  seen  it  carefully  examined,  and  the  examination 
and  full  explanation  of  the  matter  are  somewhat  new.  Mr. 
Thorn,  of  Birkacre,  Chorley,  has  used  it  for  some  time  there, 
and  at  Mayfield  some  time  before  1847.  I  recommended  it  in 
one  case  several  years  ago.  Mr.  Thorn  found  the  complete 
removal  of  lime  by  soda  to  be  very  valuable  when  printing 
delaines.  The  soap  made  with  the  lime  a  coating  which  became 
yellow  when  heated,  and  injured  the  whites.  The  double  action 
on  the  carbonates  and  sulphates  of  lime  has  not,  as  far  as  I  know, 
been  noticed. 

I  am  aware  of  certain  advantages  occasionally  received  from 
having  a  small  amount  of  impurities  suspended  in  the  water. 
If  a  boiler  be  inclined  to  leak  slightly,  even  if  in  good  order  or 
quite  new,  a  little  mud  in  the  water  gradually  fills  up  the  spaces 
— too  small  to  be  found  by  the  eye,  and  not  easily  cured  by  the 
hammer.  This  is  a  most  legitimate  use  of  insoluble  matter,  and 
I  do  not  suppose  that  it  is  advantageous  to  have  the  metallic 
surface  of  the  iron  within  the  boiler  completely  exposed.  Any- 
thing which  exposes  it  constantly  is  apt  to  prepare  the  way 
for  a  new  oxidation.  But  there  is  no  fear  of  this  great  purity 
of  water,  it  is  not  easy  to  keep  it  long  in  the  boiler  even  in  a 
moderate  condition  of  clearness.  However,  the  use  of  a  little 
lime  or  muddy  water,  to  fill  up  minute  crevices,  is  very  different 

130 


APPENDIX 

from  the  constant  accumulation  of  mud  in  the  boiler.  I  have 
tried  silicate  of  soda  by  itself  as  a  precipitant,  but  without  any 
success.  One  of  the  substances  sold  for  preventing  crust  has 
been  brought  to  me  when  writing  this  ;  it  is  composed  of  caustic 
soda  and  carbonate,  as  well  as  soap. 

EXPERIMENTS  RELATING  TO  THE  PRECIPITATION  OF  LIME  AND 

MAGNESIA. 

Nearly  all  the  lime  may  be  precipitated,  and  practically  we 
may  say  that  all  may  be.  The  following  are  fair  specimens  of 
what  may  be  obtained  in  practice — 

On  using  strong  solutions  of  carbonate  of  lime,  the  amount 
left  in  solution  was  when — 

Not  Precipitated. 

Precipitated  by  caustic  soda     .      .      1-06  grains  per  gall, 
lime      .      .      1*23 

When  tried  on  specimens  of  water  sent  by  Messrs.  Clegg,  of 
Tyldesley— 

Grains. 

Specimen  1,  amount  of  lime  left  in  a  gallon  .  0-80 

2,  „                    „                .  0-20 

3,  „                   „                .  1-06 

4,  „                    „                 .  0-13 

When  these  specimens  were  precipitated  with  great  care  and 
kept  free  from  the  influence  of  the  air,  the  whole  was  thrown 
down.  If  removed  too  early,  the  precipitate  is  not  found  at 
the  bottom ;  if  allowed  to  stand  too  long,  a  little  becomes  dis- 
solved. On  a  large  scale  we  cannot  go  farther  into  minutiae. 

When  sulphate  of  lime  exists  in  the  water  the  amount  preci- 
pitated was  as  follows — carbonate  of  soda  being  used — 

Grains  of  Sulphate  of  lime  in     Amount  of  Carbonate  of  lime  to     Amount  of  Carbonate  of  lime 
the  Gallon  of  Water.  which  the  Sulphate  is  equal.  actually  recovered. 

5-000  .  .  3-670  .  .  3-57 

4-000  .  .  2-940  .  .  2-94 

3-090  .  .  2-270  .  .  2-26 

3-000  .  .  2-200  .  .  0-68 

1-615  .  .  1-187  .  .  1-13 

1-292            .   ;  .  0-950  .  .  0-93  , 

0-969  .  .  0-712  .  .  0-71 

0-646  :  .  0-475  .  .'  0-20 

In  nearly  every  case  the  third  column  is  equal  to  the  second, 
showing  a  complete  removal  of  the  lime. 

In  another  case  water  was  precipitated  by  these  four  agents, 
with  the  following  results — 


WATER  SOFTENING  AND  TREATMENT 

Grains  of  Carbonate 
of  lime  removed. 

By  caustic  soda  .      .      .      .      ...  6-46 

,,  caustic  lime   .      .      .      .      .      .      .  2*66 

„  soda  lime ;      .      .  3-33 

,,  carbonate  of  soda 0*55 

This  water  contained  carbonate  of  lime  ;  the  carbonate  of  soda 
is  introduced  merely  to  show  that  it  can  be  of  no  advantage  in 
this  case  unless  made  caustic.  I  find  that  caustic  soda  pre- 
cipitates carbonate  of  lime  in  a  laboratory  with  much  more 
facility  than  caustic  lime  does,  and  when  a  little  excess  is  added, 
it  is  allowed  to  gather  carbonic  acid  from  the  air  without  forming 
a  crust  such  as  lime  forms.  But  this  is  not  an  objection  to  lime 
when  used  on  a  large  scale,  as  the  water  is  then  put  in  motion 
and  no  crust  forms  ;  besides  it  is  possible  on  a  large  scale  entirely 
to  avoid  excess. 

I  was  not  so  fortunate  in  precipitating  sulphate  of  magnesia 
when  it  existed  alone  in  the  water.  Indeed,  when  the  preci- 
pitate was  allowed  to  stand  long,  absolutely  nothing  was  to  be 
got.  In  the  following  five  experiments  0'08  gr.  remains,  about 
the  weight  of  two  filters — 

Amount  of  sulphate  in  solution   .    12-50     10-00     7-50     5-00     2-50 
Amount  of  precipitate       .      .      .      0-08       0-08     0-08     0-08     0-08 

A  fair  specimen  of  the  experiments  with  carbonate  of  soda  and  a 
little  caustic  soda,  is — 

Grains  of  Sulphate  of          Grains  of  Carbonate  of          Carbonate  of  magnesia, 
magnesia  in  solution.  magnesia.  precipitate. 

5-0  3-5  .      .          1-60 

3-0  2-1  .      .          2-07 

2-0  1-4  .      .          1-14 

This  shows  that  there  is  a  possibility  of  entirely  removing  it. 
When  precipitated  along  with  lime  there  is  less  need  of  care, 
and  three  results  gave  of  carbonate  remaining  unprecipitated — 

Grains  in  a  gallon.  .  .  .    1'30      0'82      0-407  grains. 

But,  again,  another  gave  3' 7,  this  depending  on  the  management 
of  the  precipitate,  as  explained,  and  partly  on  the  amount  of 
alkaline  salts  in  the  water.  At  the  same  time,  the  precipitation 
of  the  magnesia  from  the  sulphate  of  magnesia  is  not  of  import- 
ance, as  that  salt  is  so  very  soluble  as  to  be  incapable  of  making 
a  crust  unless  with  the  greatest  carelessness,  and  even  then  water 
would  be  sufficient  to  remove  it. 

132 


APPENDIX 

SUMMARY. 

I  will  now  sum  up  the  conclusions  to  which  I  have  come  relating 
to  these  classes  of  waters  : — 

1.  That  chalk  waters  are  best  treated  by  Clark's  process  ; 
that  is,  by  caustic  lime. 

2.  That  mixed  chalk  and  gypsum  waters  can  be  precipi- 
tated completely  by  caustic  soda. 

3.  That  gypsum  waters  may  be  precipitated  by  carbonate 
of  soda,  with  the  addition  of  a  minute  quantity  of  caustic 
soda. 

4.  That  these  precipitations  are  far  more  elegant,  com- 
plete, efficient,  and  satisfactory  when  made  in  a  separate 
vessel,  the  pure  water  alone  entering  the  boiler. 

5.  That  in  many  cases  the  precipitation  answers  very  well 
conducted  in  the  boiler. 


RULES  FOB  WATERS  (1  AND  2)  AND  THEIR  MIXTURES. 
Rule  1. 

Water  No.  1. — Carbonate  of  lime  alone  in  the  water. 

The  following  is  the  method  of  treating  1,000  gallons — 

For  every  grain  of  carbonate  of  lime,  per  gallon  =  1,000 
grains  per  1,000  gallons,  use  1,060  grains  of  carbonate 
of  soda,  made  caustic  with  560  grains  of  burnt  lime. 

Rule  2. 

Water  No.  2. — Sulphate  of  lime  in  the  water. 
Treat  1,000  gallons  so— 

For  every  grain  of  sulphate  of  lime,  per   gallon  =  1,000 

grains  per  1,000  gallons,  use  779*4  grains  of  carbonate 

of  soda. 

Rule  3. 
Nos.  1  and  2.— Mixed. 

a.  For  every  grain  of  carbonate,  per  gallon,  add  accord- 

ing to  Rule  1. 

b.  When  the  sulphate  of  -lime  is  not  above  8  to  6  of  car- 

bonate neglect  it  entirely. 

c.  If  there  be  any  sulphate  beyond  that  amount,  treat  it 

according  to  Rule  2. 

QUESTIONS  REQUIRING  INVESTIGATION. 

Effect  of  perfectly  pure  water  in  a  boiler. 
Effect  of  water  containing  only  a  little  carbonic  acid. 
Effect  of  precipitation  in  a  boiler  both  by  soda  and  by  lime. 
Fuller  account  of  substances  sold  for  preventing  and  destroying 
crusts. 

133 


WATER    SOFTENING   AND    TREATMENT 

I  shall  now  add  the  analysis  of  some  waters  which  have  been 
sent  to  me  from  this  district,  and  some  others  previously 
examined. 


WATER  SENT  BY  THOMAS  CLEGG  &  Co.,  OF  TYLDESLEY. 

No.  1  is  from  a  well  at  Tyldesley. 

No.  2  is  from  the  brook  in  the  morning. 

No.  3  is  from  the  brook  at  noon. 

Grains  per  gallon. 

No.  1.     No.  2.    No.  3. 

Carbonate  of  lime       .......      8-119  4-04         3-47 

Sulphate  of  lime   .      .      ...      ...      .      .      8-570  18-83       19-97 

Carbonate  of  magnesia    .      .      ...      .      7-700  7-94         5-57 

Oxide  of  iron 0-220  0-75         0-72 

Silica 0-850  1-74         1-51 

Chloride  of  sodium,  alkaline  carbonates,  and 

loss                                                                       1-341  0-50           — 


Inorganic  matter 27-80         33-8         31-24 

Organic  matter 3-85  4-6  4-00 

Total 31-68          38-4         35-24 

Hardness 23-00         21-0         21-00 

Hardness  after  liming 9-50          12-9          12-60 

No.  3  analysis  is  exact  in  the  lime,  which  is  the  essential  point 
and  was  more  than  once  ascertained  ;  also  in  sulphates  ;  but 
the  alkalies  and  the  magnesia  are  a  little  uncertain.  However, 
as  it  was  an  accidental  condition  of  things,  on  account  of  water 
flowing  from  other  works,  it  was  not  worth  the  trouble  of  ascer- 
taining it  more  exactly  ;  it  would  not  be  the  same  two  days 
together. 

WATER  FROM  DEEP  WELL  AT  SEEDLEY  PRINT  WORKS. 

Sulphate  of  lime         .      .      .  2-714  grains  per  gallon. 

Carbonate  of  lime      .      .      .  6-115 

Carbonate  of  magnesia    .      .  2-050 

Silica 0-360 

Carbonic  salt          ....  1-650 

Other  alkaline  salts,  and  loss .  0-111 

Total  inorganic  matter.    13-000 


Hardness 10-9  degrees. 

Hardness  after  boiling  .  .  5-2  ,, 
Hardness  before  liming  .  .  5-2  ,, 
Alkalinity 5-6 

134 


APPENDIX 

SPRING  WATER  AT  SEEDLEY. 

Sulphate  of  lime       ....         9-45  grains  per  gallon. 
Carbonate  of  lime     ....          1-51  „ 

Magnesia  = 

Carbonate  of  magnesia        .      .          4-74  but  most  as  chloride, 

and  to  be  treated  as 
if  carbonate. 

Silica 0-61 

Oxide  of  iron             ....          0-66  ,, 

Alkaline  salts 0-49 

Total  inorganic  matter      .        17*46  „ 


Organic  and  volatile  matter     .          5*20  some  of  this  is  nitric 

acid  from  nitrates  in 
the  water. 

Hardness 16-50  degrees. 

After  boiling      ....        10-50       „ 
After  precipitating  by  lime.       10-45       „ 

Alkalinity 2-40 

Chlorine  in  a  gallon       .      .      .          0-42  the  alkalies  not  sepa- 

—      rately  determined. 

BROOKS  NEAR  LEVENSHULME. 

1  2 

Carbonate  of  lime  ....    11-52  2-76 

Carbonate  of  magnesia      .      .      2*09  4*04 

Sulphate  of  magnesia         .      .      1-06  0-51 

Sulphate  of  soda     .      .      .      .2-65  2-50 

Sulphate  of  potash       .      .      .      1-76  1-56 

Chloride  of  magnesium      .      .      0-69  1-32 

Silica 0-52  0-34 

Oxide  of  iron  and  alumina    .      0-50  0-14 
Nitrate  of  magnesia     .      .      .      0-69 


21-48  13-17 
Error  in  excess              .      .      .        -08 

Total  obtained     .      .21-40 
WATER  FROM  NEAR  BURY. 

Surface.  Well. 

Sulphate  of  lime     ....      1-265  1-292 

Sulphate  of  magnesia         .      .      0-363  3-950 

Carbonate  of  magnesia      .      .      0-110  3-000 

Silica 0-750  0-320 

Alkaline  salts                                   0-980  2-420 


Inorganic  matter    ....      3-468          10-980 
Organic  matter 0-780  1-740 


The  first  needs  no  treatment — the  second  very  little. 

135 


WATER    SOFTENING   AND    TREATMENT 

WATERS  FROM  WIGAN. 
Specimens  of  Surface  Water. 

123 

Sulphate  of  lime  .  .  .  8-67  9-72  5-77 
Carbonate  of  lime  .  .  .  1-78  0-48  4-65 

Phosphate  of  lime  .  .  0-06  0-02  slight 
Carbonate  of  magnesia  .  1-89  1-44  4-67 
Oxide  of  iron  ,  .  .  0-05  0-42  0-06 
Chloride  of  potassium.  .  0-54  0-43  0-51 
Salts  of  soda  ....  4-07  1-53  0-54 

Silica .      0-45         0-63         0-48 

Organic  matter.      .      .      .      6-00       15-40         5-82 

23-41       30-07  22-50 


Inorganic  matter    .      .      .    17-41       14-67       16-68 

In  analysing  waters  for  practical  purposes,  I  find  it  much 
more  convenient  to  put  the  sulphuric  acid  first  to  the  lime.  It 
is  in  fact  necessary,  in  order  to  obtain  the  end  in  view,  although 
it  may  be  objected  to  on  theoretical  grounds. 

PART  SECOND. 

The  water  from  Rochdale  Canal  has  frequently  been  com- 
plained of,  on  account  of  the  property  it  has  of  dissolving  iron 
and  of  causing  the  oxidation  of  still  more  of  that  metal  than 
it  can  dissolve.  I  first  heard  at  Littleborough  of  this  quality 
of  the  canal  water,  and  obtained  a  specimen  from  that  village. 
I  found  it  to  be  slightly  alkaline,  and  not  to  contain  much  car- 
bonic acid.  Further  inquiry,  however,  showed  a  very  different 
condition  of  things.  The  acidity  at  Littleborough  has  been 
found  to  be  equal  to  the  saturation  of  0-070-0-140  grains  of 
carbonate  of  soda  per  gallon.  At  0*140  the  amount  in  sulphuric 
acid  would  be  equal  to  0-101  or  101-  grains  in  1,000  gallons. 

Near  Manchester  the  acidity  in  the  canal  rises  higher,  and  has 
been  found  equal  to  3-99  grains  of  carbonate  of  soda  per  gallon, 
although  in  Ancoats  it  was  generally  alkaline  or  neutral.  3*99 
grains  must  be  considered  a  very  large  amount  when  it  is  in 
contact  with  iron.  J 

The  mode  of  dealing  with  such  water  is  simple,  as  it  only 
requires  to  be  treated  with  an  alkali.  For  the  specimen  taken 
near  Manchester  the  amount  of  carbonate  of  soda  necessary  is 
3-99  grains  per  gallon,  or  1  Ib.  to  1,754  gallons.  Lime  will  also 
neutralize  the  acidity,  but  it  is  preferred  not  to  add  lime. 

The  amount  of  carbonate  of  soda  required  for  neutralizing 
water  of  0*070  acidity,  such  as  is  frequent  at  Littleborough,  is 
70  grains  per  1,000  gallons. 

136 


APPENDIX 

Amount  required  to  neutralize  1,000  gallons  of  water  of  the 
acidity  of  3*99— 

Carbonate  of  soda .      .     3,990  grains    =  9'12  ounces, 
or  Caustic  lime    .      .      .      2,031       „       =     4-6     „ 
Amount  of  water  neutralized  by  1  Ib.  of  Carbonate 

of  soda 1,754  gallons. 

Amount  of  water  neutralized  by  1  Ib.  of  Caustic 

lime     ...........    3,446 

When  soda  is  used  this  neutralization  may  take  place  in  the 
boiler  without  causing  much  inconvenience,  the  amount  of 
precipitate  not  being  great,  especially  in  the  case  of  the  Little- 
borough  water.  If  lime  be  used,  it  is  much  better  to  have  a 
separate  vessel  or  tank  for  the  mixture.  In  any  case  there  is  no 
difficulty  in  curing  this  evil  which  has  been  so  widely  complained 
of. 

Rochdale  Canal  at  Littleborough — 

Sulphate  of  lime        .      .      ...      .      .  1-916 

Sulphate  of  magnesia     .      .      .      .      .      .  0-642 

Chloride  of  magnesium 0-318 

Chloride  of  iron 0-467 

Silica 0-380 

Other  salts  0-187 


3-900 

Organic  matter 1-040 

Hardness 0-140 

Acidity — when  acid  .......     0-070 

Rochdale  Canal,  near  Newton  Heath — 

Sulphate  of  lime    •    .      .      .'    .      .      .      .  2-50 

Sulphate  of  magnesia "  .  1-90 

Chloride  of  iron  ...,....-  0-28 

Silica    .      .      ...      .      .      .      .      .      .      .  0-75 

Alkaline  salts       .      .      .    - .      .      .      .    " .  2-26 

Sulphate  of  alumina       .      .      .      .    s.      .  0-09 

7-03 


Rochdale  Canal,  at  Messrs.  M'Connel's,  Ancoats — 

Sulphate  of  lime        ...      .      .      .      .  4-12 

Sulphate  of  magnesia     .      .      .    '.      .      .  2-88 

Sulphate  of  iron        .......  0-43 

Alumina  and  oxide  of  iron       .      .      .      .  0-14 

Alkaline  salts 1-49 

9-06 
137 


WATER    SOFTENING   AND    TREATMENT 

Hardness \  6-20 

Alkalinity .      .      .        0-07 


In  order  to  obtain  a  complete  answer  to  all  the  questions 
suggested  by  the  varying  acidity  of  the  Rochdale  Canal,  it  would 
be  necessary  to  have  very  numerous  examinations  made  at 
various  times  and  in  many  places.  Many  causes  contribute  to 
its  acidity,  but  I  am  inclined  to  think  that  one  only  renders  it 
peculiarly  hurtful  to  boilers.  The  water  at  Littleborough  was 
from  O07-0-14  of  acidity,  but  some  taken  from  a  boiler  which 
had  been  boiling  down  for  a  month  was  9' 8,  whilst  another  rose 
to  21*3.  This  was,  in  fact,  a  solution  of  iron.  When  the  acid 
water  at  Littleborough  was  boiled  down  far,  it  gave  off  muriatic 
acid,  and  when  boiled  still  farther,  almost  to  dryness,  it  gave 
off  sulphuric  acid.  A  minute  quantity  of  alumina  was  got  in 
solution.  These  facts  indicate  the  existence  of  waters  flowing 
into  the  canal  having  acid  salts  in  solution,  sulphates  of  iron,  and 
of  small  quantities  of  alumina.  Indeed  the  existence  of  such 
water  is  not  a  supposition,  although  I  have  not  inquired  at  what 
point  it  enters  the  canal.  Possibly  it  may  flow  in  at  various 
points.  At  Littleborough  a  manufacturer  was  using  water  from 
a  well  near  the  canal  strongly  impregnated  with  sulphate  of  iron. 
He  used  it  to  avoid  the  water  of  the  canal,  but  he  had  chosen 
the  worse,  and  the  deposit  from  the  boiler  was  rich  in  oxide  of 
iron.  This  will  point  out  one  source  from  which  the  canal  obtains 
impure  water  ;  there  may  be  thousands  of  others.  Or,  as  the 
water  is  not  at  all  times  equally  acid,  the  acidity  may  rise  from 
occasional  discharges  from  coalpits  also,  or  even  from  manufac- 
tories. In  one  other  respect  the  water  of  Littleborough  has  a 
slightly  increased  inclination  to  act  on  metals,  both  lead  and 
iron,  because  of  the  greater  amount  of  chlorides  in  it  than 
waters  from  the  hills  generally  contain.  In  this  respect  even 
the  water  which  is  not  acid  will  be  injurious  when  it  has  been 
much  boiled  down.  The  amount  of  chlorides  found  in  water  from 
a  boiler  was  just  70  times  greater  than  in  the  canal  water,  so 
much  greater  that  the  solution  of  the  sulphate  of  lime  was  pre- 
vented. From  this  water  alkalies  throw  down  a  bulky  white 
precipitate. 

On  trying  the  action  of  Rochdale  Canal  water  at  Littleborougfe 
and  of  Manchester  pipe  water  in  dissolving  iron  wire,  I  founa 
that  in  a  month  the  canal  water  had  oxidized  6'7  per  cent.,  and 
the  Manchester  water  only  4-07.  This,  of  course,  was  under  cir- 
cumstances favourable  to  oxidation  ;  boilers  are  not  often  acted 
upon  so  violently. 

Peaty  matter  is  another  cause  of  the  acidity  of  water.  The 
moss  water  is  alkaline,  in  warm  autumns  especially,  becoming 
acid  in  winter.  I  should  expect  this  acid  to  act  although  slightly 


APPENDIX 

on  the  boilers,  but  experiments  have  not  yet  favoured  that  view, 
although  I  have  obtained  water  from  Dumfriesshire  much 
browner  than  any  water  to  be  found  in  Lancashire,  and  also  very 
acid  from  humic  or  peaty  acids.  Although  this  is  interesting, 
and  will  probably  engage  my  attention,  it  has  only  a  limited 
bearing  on  the  manufactures  of  the  neighbourhood.  The 
Littleborough  reservoir,  when  tried  in  December  1859,  was 
found  to  be  decidedly  alkaline  ;  at  the  same  time  the  canal  was 
neutral  at  Littleborough.  The  variations  are  many,  and  scien- 
tifically it  might  be  interesting  to  inquire  into  many  questions 
readily  suggested  to  a  chemist ;  but  practically  I  can  only  add, 
that  the  acidity  must  be  removed  by  alkali,  and  even  when  this 
is  done  it  is  necessary  to  empty  the  boiler  or  blow  out  a  large 
portion  of  the  water  at  frequent  intervals.  These  intervals  must 
be  more  frequent,  according  as  the  situation  is  nearer  Man- 
chester. 

Mr.  M'Connel  was  kind  enough  to  give  me  a  great  deal  of 
information  and  to  supply  me  with  many  specimens  ;  I  did  not 
analyse  all  of  them  fully,  as  I  found  that  they  were  not  acid, 
and  that  their  action  on  the  boiler  chiefly  arose  from  their  con- 
taining a  good  deal  of  chlorine,  and  being  unprotected  by 
alkalinity. 

RULE  FOR  ACID  WATERS. 

Add  carbonate  of  soda,  or  an  alkali.  A  degree  of  acidity  is 
the  same  as  the  amount  of  carbonate  of  soda  required  to  neutral- 
ize it.  Therefore,  for  every  degree  of  acidity  add  one  grain  of 
carbonate  of  soda  per  gallon.  For  O'lO  deg.  add  O10  of  carbonate 
of  soda  per  gallon,  made  caustic  or  otherwise. 

I  would  prefer  carbonate  of  soda,  and  to  precipitate  in  a 
separate  vessel.  In  this  way  not  only  is  the  acid  removed,  but 
the  gypsum  decomposed  according  to  the  rules  in  Part  First. 
Before  the  canal  approaches  near  Manchester,  the  water  contains 
so  little  lime  that  this  precaution  is  less  required. 


139 


Appendix  No.    2 


TABLE  IX. 
SOLUBILITY  or  GASES  IN  WATER  AND  ALCOHOL  (BUNSEN). 


Gas. 

Volume  of  gas  dissolved  in  1  Vol. 

Of  Water. 

Of  Alcohol. 

At  32°  F. 

At  59°  F. 

At  32°  F.         At  59°  F. 

Ammonia 

1049-6 

727-2 

_                     _ 

Hydrochloric    Acid 

505-9 

458-0 

—                     — 

Sulphurous  Acid     . 

68-86 

43-564 

328-62 

144-65 

Sulphuretted 

Hydrogen 

4-37 

3-2326 

17-891 

9-539 

Chlorine 

Solid. 

2-368 

— 

— 

Carbonic  Acid  . 

1-797 

1-002 

4-3295 

3-1993 

Protoxide  of 

Nitrogen 

1-305 

0-0778 

4-1780 

3-2678 

Olefiant  Gas 

0-2563 

0-1615 

3-5950 

2-8825 

Binox.  of  Nitrogen 

— 

— 

0-31606 

0-27978 

Marsh  Gas     . 

0-0545 

0-03909 

0-52259 

0-4828 

Carbonic    Oxide 

0-03287 

0-02432 

0-20443 

0-20443 

Oxygen    . 

0-04114 

0-02989 

0-28397 

0-28397 

Nitrogen  . 

0-02035 

0-01478 

0-12634 

0-12142 

Air      .... 

0-02471 

0-01795 

— 

— 

Hydrogen 

0-01930 

0-01930 

0-06925 

0-06725 

All  gases  are  more  or  less  soluble  in  water  and  the  solubility 
increases  as  the  elasticity  of  a  gas  decreases.  Hence  the 
increase  at  lower  temperature  and  greater  pressure.  ^  :< 

Dr.  Henry  stated  that  the  volume  of  a  gas  dissolved  was  tne 
same  at  all  pressures  for  any  given  temperature.  Hence  the 
rule  that  the  weight  of  gas  dissolved  increases  with  the  pressure. 
In  the  table  above  the  volumes  stated  are  those  reduced  to 
32°  F.  and  29-92  inches  of  mercury. 

In  case  of  a  mixed  gas  the  volume  dissolved  of  each  con- 
stituent will  be  proportionate  to  the  relative  volume  of  each  gas 
multiplied  of  its  coefficient  of  solubility.  Thus,  if  air  be  taken 

140 


APPENDIX 

as  an  example  of  a  mixture  of  1  of  oxygen  and  4  of  nitrogen, 
the  proportion  of  each  gas  dissolved  will  be  at  59°  F. 

Oxgyen      |  x  0-02989  =  0-00597 
Nitrogen    -|  X0'01478  =  0-01162 

0-01759  of  air. 


141 


Appendix  No.   3 


INFLUENCE  OF  SALTS  UPON  THE  BOILING  POINT  OF 

WATER 

THE  presence  of  salts  in  water  invariably  raises  the  tem- 
perature of  ebullition.  This  depends  upon  the  adhesion 
of  the  salt  to  the  water. 

Legrand  (Annales  de  Chimie,  II.  lix.  423)  published  the  follow- 
ing table. 

In  Table  X.  the  weights  are  taken  of  the  anhydrous  salts. 

Experiments  are  wanting  to  determine  the  action  of  salts  at 
higher  pressures  and  temperatures  but  it  may  be  assumed  that 
the  bad  effect  of  soda  in  hindering  the  transmission  of  heat  to 
water  from  heated  plates  has  some  connexion  with  this  subject. 

TABLE  X. 

SOLUBILITY  OF  SALTS  AND  TEMPERATURE  OF  EVAPORATION. 


Salt. 

Parts  of 
100  of 

Salt  per 
Water. 

Boiling 
Point 

Parts  of 
Salt  per 

1  (\o  Of 

Name  of  Salt. 

212°  F. 

to 
213-3° 

213-8°  F. 
to 
215-6° 

of 
Saturated 
Solution. 

1UU  OI 

Water 
when 
Saturated. 

Nitrate  of  Soda      .      .      . 

9-3 

9-4 

250°  F 

224-8 

,,       ,    Ammonia  . 

10-0 

10-5 

— 

Unlimited 

,    Potash.      .      . 

12-2 

14-2 

240 

335-1 

Chlorate  ,            „ 

14-6 

14-6 

220 

61-5 

Chloride  ,   Sodium 

7-7 

5-7 

227 

41-2 

,,         ,   Potassium 

9-0 

8-1 

227 

59-4 

Carbonate  of  Soda 

14-4 

12-3 

220 

48-5 

Acetate        „     „           .      . 

9-9 

7-7 

256 

209-0 

Chloride  of  Barium 

19-6 

12-9 

220 

60-1 

Tribasic  Phosphate  of  Soda 

and  Water     .... 

21-0 

19-8 

224 

112-6 

Sal  Ammoniac 

7-8 

6-1 

238 

88-9 

Chloride  of  Calcium 

10-0 

6*5 

355 

325-oi 

Acetate  of  Potash 

10-5 

9-5 

336 

798-2 

Carbonate  of     ,,            . 

13-0 

9-5 

275 

205-0 

Nitrate  of  Lime 

15-0 

10-3 

304 

362-2 

Chloride  of  Strontium 

16-7 

8-5 

244 

117-5 

Tartrate  of  Potash        .      £ 

26-9 

20-3 

238 

296-2 

The  steam  which  rises  from  the  above  at  once  assumes  the 

142 


APPENDIX 

temperature  proper  to  the  superincumbent  pressure,   the  in- 
fluence of  the  salt  ceasing  at  the  surface  of  the  water. 

The  more  soluble  salts  do  not  necessarily  produce  the  higher 
boiling  points. 

(See  also  Appendix  No.  4.) 


143 


Appendix   No.   4 

WATER  AND  ITS  PROPERTIES 

PURE  water  is  a  compound  of  2  parts  of  hydrogen  and  16 
parts  of  oxygen.  Its  specific  gravity  is  unity  being  the 
basis  on  which  all  other  specific  gravities  are  stated. 

To  heat  1  Ib.  of  water  1°  F.  from  32°  to  33°  requires  1 
British  thermal  unit. 

To  heat  1  kilo.  =2-204  Ib.  1  degree  Centigrade  from  0°  to 
10  =  1|°F.  requires  1  calorie  of  heat  =  3'9683  B.Th.U. 

Thus  1  B.Th.U.  =0-252  calorie. 

One  imperial  gallon  of  water  at  62°  F.  =  10  Ib.  and  measures 
277*479  cubic  inches.  The  American  gallon  weighs  8J  Ib.  and 
measures  231  cubic  inches. 

The  litre  of  water  weighs  1  kilo.  =2-204  Ib.  and  1,000  kilos., 
therefore,  weigh  nearly  1  ton. 

A  column  of  water  1  foot  high  exerts  a  pressure  of  0-434  Ib. 
per  square  inch,  and  a  pressure  of  1  Ib.  conversely  represents  a 
water  pressure  of  2*3  feet.  Hence  one  atmosphere  of  pressure 
equals  33  -8  feet  of  water. 

Water  is  nearly  incompressible,  the  coefficient  at  0°  C.  = 
32°  F.  being  0-000052,  and  at  nearly  35°  C.  =  127°  F.  =0-00041. 
It  is  thus  negligible  for  the  purposes  of  this  book.  The  heat 
expansion  is  more  considerable  but  does  not  amount  to  5%  under 
atmospheric  pressure.  The  following  table  XI.  gives  the  weight 
per  cubic  foot  at  different  temperatures  Fahr. 


TABLE  XI. 

WEIGHT  OF  WATER  PEE-  CUBIC  FOOT. 


Temp. 

Weight. 

Temp. 

Weight. 

Temp. 

Weight. 

212 

59-71 

350 

55-52 

500 

49-61 

250 

58-81 

400 

53-64 

550 

47-52 

300 

57-26 

450 

50-66 

62 

62-2786 

102 

62-00 

158 

61-00 

203 

60-00 

144 


APPENDIX 


Water  solidifies  at  32°  F.  =0°  C.  and  ice  has  a  specific  gravity 
of  0-922  and  a  specific  heat  of  0-504. 

Water  at  32°  F.  solid  absorbs  142  B.Th.U.  in  becoming  liquid 
at  32°  F. 

The  latent  heat  of  water  is  thus  142  B.Th.U.  per  Ib.  =78-86 
calories  per  kilo. 

The  specific  heat  of  water  being  1-00  at  32°  F.  increases  slowly 
with  temperature  and  becomes  1-0568  at  446°. 

As  the  expansion  of  water  is  greater  than  its  rise  of  specific 
heat  the  total  heat  of  water  per  cubic  foot  will  not  increase  as 
quickly  as  the  temperature. 

The  evaporation  of  1  Ib.  of  water  at  212°  into  steam  at  212°  F. 
demands  966  B.Th.U, 

Sea  water  contains  38  parts  per  1000  of  dissolved  matter,  of 
which  25  to  28  parts  are  common  salt  or  Nad.  The  other 
salts  of  sea  water  are  magnesium  chloride  and  sulphate,  cal- 
cium sulphate,  potassium  sulphate  and  chloride,  bromide  of 
soda,  the  carbonates  of  lime  and  magnesia  and  others  of  less 
importance. 

The  annexed  table  gives  a  few  of  the  figures  relative  to  the 
solubility  of  salts  in  parts  per  100  of  water. 

(See  also  Appendix  No.  3.) 

TABLE  XII. 

SOLUBILITY  OF  SALTS. 


CQlf 

Temperature  F. 

32°F. 

70°  F. 

212°  F: 

Calcium  Chloride 

400 

_ 

_ 

Magnesium  Sulphate     . 
Potassium  Carbonate    . 

24-7 
100 

35-0 
80-0 

130 

Chlorate 

3-33 

8-0 

60 

Chloride 

29-21 

34-0 

60 

Nitrate  . 

13-32 

30-0 

240 

Sulphate 
Sodium  Carbonate 
Bicarbonate 

6-97 
6-9 

12-0 
21-7 
9-6 

26 
45-1 

Chloride 

35-5 

36-0 

39-6 

Sulphate 
Barium  Chloride 

5-02 
35-0 

22-0 

42-6 
60-0 

Calcium  Carbonate  . 

0-0036 

— 

— 

,,      Sulphate    . 
Magnesium  Chloride 
,,           Carbonate   . 

0-23 
200-0 
0-02 

— 

0-21 

145 


WATER  SOFTENING  AND  TREATMENT 

SOLUBILITY    OF  THE  CARBONATES   AND  OXIDES    OF   LIME  AND 
MAGNESIA  AT  60°  F.  AND  212°  IN  GRAINS  PER  IMPERIAL  GALLON. 


66°  F. 

212°  F. 

Carbonate  of  Lime  CaCO-j 

2-5 

1-5 

Bicarbonate  CaO.2CO2      •      .      ... 

GOO 

0 

Calcium  Oxide  CaO.     .      .      .      ... 
IVEagnesium  Carbonate  JVIgCO-i 

93-0 
1-5 

1-5 

Bicarbonate  MgO2CO2    ..... 
Magnesium  Oxide  MgO  
Calcium  Sulphate  CaSO4  

50-0 
0-15 
161-0 

0 



146 


Section   II 


AIR    PUMPS,    CONDENSERS,    AND 
CIRCULATING  PUMPS 


147 


CHAPTER  XVIII 
HEAT 

IN  questions  of  condensation  and  feed  heating  some  know- 
ledge of  heat  and  its  effects  is  necessary  to  enable  the 
engineer  to  make  correct  calculations. 

We  only  know  heat  by  its  effects  and  assume  it  to  consist 
in  atomic  or  molecular  vibration. 

A  body  is  said  to  be  hot  when  it  can  communicate  heat 
to  other  bodies  at  a  less  temperature,  but  temperature  is 
merely  that  quality  of  heat  which  is  sensible  to  our  nerves. 
Temperature  heat  is  measured  by  its  effects  in  causing 
bodies  such  as  mercury  to  expand,  and  also  by  the  electric 
current  that  is  caused  to  flow  when  two  different  bodies  in 
circuit  are  equally  exposed  to  heat  as  in  the  thermopile. 
But  temperature  is  no  measure  of  heat.  It  is  merely  that 
quality  which  enables  heat  to  pass  from  one  body  to  another, 
and  in  this  way  a  body  containing  little  heat  can  be  made 
to  pass  some  of  its  small  store  to  a  body  containing  more 
heat  at  a  less  temperature.  Thus  a  pound  mass  of  iron  at 
100°  F.  of  temperature  will  supply  heat  to  a  pound  mass  of 
water  at  any  lower  temperature.  Yet  the  water  contains 
several  times  as  much  heat  as  iron.  The  actual  quantity 
of  heat  is  given  usually  by  stating  how  many  pounds  or 
kilogrammes  of  water  can  be  raised  one  degree  of  tempera- 
ture F.  or  C.,  by  a  given  amount  of  heat.  The  two  quantities 
of  heat  necessary  for  1  Ib.  or  1  kilo,  are  called  the  British 
Thermal  Unit  and  the  Calorie  respectively. 

Specific  Heat. 

That  property  of  a  body  which  determines  how  much 
heat  is  represented  by  a  rise  or  fall  in  that  body  of  1°F.  or 

149 


WATER    SOFTENING   AND    TREATMENT 

1°  C.  is  called  the  specific  heat  of  the  body.  Thus  the 
thermal  unit  which  raises  1  Ib.  of  water  through  1°  F.  will  raise 
5  Ib.  of  some  other  body  through  1°  F.  The  specific 
heat  of  the  other  body  is  therefore  4  =  0*2  relative  to  that 
of  water  which  is  rated  at  unity  as  standard. 

The  Fahrenheit  thermometer  divides  the  difference  of 
temperature  between  the  freezing  point  of  water  and  its 
boiling  point  into  180°  parts.  The  Centigrade  thermometer 
makes  100  divisions  only.  Thus,  pure  water  under  the 
mean  atmospheric  pressure  of  14»7  Ib.  boils  at  212°  F.  = 
100°  C.  and  it  freezes  at  32°  F.  =  0°  C. 

Evidently  there  must  be  no  confusion  of  thought  between 
quantity  of  heat  and  temperature.  If  1  Ib.  of  water, 
containing  100  B.Th.U.  above  some  given  temperature,  is 
said  to  contain  heat  =  H,  then  if  it  be  further  heated 
through  10°  F.  it  will  contain  H  +  T  very  nearly,  or  110 
B.Th.U.  But  it  is  not  strictly  correct  so  to  express  the 
operation,  though  the  result  is  correct  practically  simply 
because  the  specific  heat  of  water  is  so  nearly  constant  at  all 
temperatures  concerned  in  this  book  that  the  temperature 
rise  practically  equals  the  added  number  of  heat  units. 
But  such  a  formula  would  only  serve  with  water.  It  would 
be  wrong  for  other  cases,  especially  of  mixtures  of  two 
different  substances. 

A  mass  of  1  Ib.  of  iron  heated  to  132°  F.  contains 
12-98  B.Th.U.  measured  above  32°  F.  A  pound  mass  of 
water  at  82°  F.  contains  approximately  50  B.Th.U.  above 
32°  F.  Yet  if  the  iron  is  placed  in  the  water,  heat  will  leave 
the  iron  which  already  contains  so  little  and  will  enter  the 
water  already  so  well  furnished.  The  final  temperature  will 
be  removed  from  the  initial  temperature  of  the  water  about 
5°  F.  only  and  the  iron  will  lose  45°  F.  of  the  initial  difference 
of  50°  F.  The  temperature  of  the  two  substances  will  then 
be  about  87°  F.,  showing  that  the  specific  heat  of  the  iron 
is  about  one-ninth  that  of  water. 

Latent  Heat. 

Latent  heat  is  heat  which  ceases  to  show  temperature 
effects,  being  otherwise  employed  in  maintaining  a  body  in 

150 


HEAT 

a  changed  state.  Thus  water  is  said  to  have  a  latent  heat 
of  142-6  B.Th.U.,  because  in  melting  1  Ib.  of  ice  from 
32°  F.  to  water  at  32°  F.  nothing  is  shown  by  the  thermo- 
meter, yet  the  heat  has  gone  into  the  ice  and  is  all  absorbed 
in  keeping  up  the  molecular  activity  of  liquidity  and  enables 
the  water  to  remain  liquid  or  mobile.  This  same  water, 
if  further  heat  be  added,  now  shows  rises  in  temperature 
until  it  reaches  212°  F.  Then  no  further  rise  takes  place, 
yet  the  water  all  disappears  as  steam  at  212°  F.,  and  no 
fewer  than  965-7  B.Th.U.  disappear  with  it.  Thus  we  say 
that  the  latent  heat  of  steam  is  965*7  because  this  amount 
of  heat  is  hidden  in  preserving  the  high  molecular  mobility 
necessary  to  keep  water  in  the  gaseous  state.  In  this  volume 
therefore  the 

Unit  of  Heat 

is  that  amount  of  heat  necessary  to  raise  the  temperature  of 
1  Ib.  of  water  through  1°  F.,  at  or  near  39-1°  F.  It  is 
nearly  the  same  at  higher  temperatures  and  for  the  purposes 
of  this  book  the  unit  of  heat  may  be  taken  equal  to  the  above 
duty  at  any  temperature  of  water  used  herein.  The  calorie 
or  metric  heat  unit,  is  the  heat  required  to  raise  1  kilo,  of 
water  through  1°  C.  at  or  near  4°  C,  water  being  at  maxi- 
mum density  at  39-1°  F.  =  4°  C. 

Since  1  kilo.  =  2-204  Ib.  and  1°  F.  =  |°  C.,  it  follows 
that  2-204  x  9  -=-  5  =  3-968  =  number  of  B.Th.U.  in  1 
calorie. 

Consequently  1  B.Th.U.  =  0-252  calorie. 

1  cal.          =  3-968     B.Th.U.    or    approxi- 
mately the  ratio  is  1  :  4  for  most  ordinary  calculations. 

Unit  of  Work. 

The  relation  of  heat  to  work  units  will  not  be  much 
needed  in  this  book.  It  will  suffice  merely  to  say  that  the 
mechanical  equivalent  of  heat  is  as  follows — 

1  B.Th.U.  =  772  foot-lb. 

1  calorie      =  423-55  metre-kilos.  =  3063-54  foot-lb. 


WATER  SOFTENING  AND  TREATMENT 


If  we  take  the  more  recent  determinations  of  the  equiva- 
lent we  have — 

1  B.Th.U.  =  778  foot-lb.  =  107-78  kilogramme-metres. 
1  cal.  ==  426-84  kilogramme-metres  =  3087-3  foot-lb. 

TABLE  OF  LATENT  HEAT  VALUES. 


Per  Pound. 

Per  Kilo. 

B.Th.U. 

Cal. 

Cal. 

B.Th.U. 

Ice  to  Water.     Both  at  32° 
Water  to  Steam.  Both  at  212° 

142-6 
965-7 

35-93 
243-3 

79-2 
536-4 

314-3 
212-8 

In  steam  at  100°  P.  or  thereabouts,  which  is  practically 
the  temperature  of  condensers,  there  are  very  approximately 
1,000  B.Th.U.  of  latent  heat.  This  number  is  thus  useful  for 
rapid  calculation.  One  pound  of  steam  will  have  to  lose 
this  amount  and  a  little  more.  If  1  Ib.  of  cooling  water 
disappears,  it  must  gain  the  amount  and  a  little  more.  The 
round  figure  will  serve  very  well  for  our  purpose. 

It  will  now  be  obvious  that  while  calculations  are  often 
made  on  secondary  facts,  it  is  always  better  to  start  from  a 
definite  datum  line. 

Many  engineers  ignore  the  thermal  unit  altogether,  and 
if  asked  how  to  find  the  amount  of  air  to  cool  the  condensing 
water  of  a  certain  power  plant,  they  would  assume  so  many 
pounds  of  evaporation  per  pound  of  fuel,  so  much  steam 
per  h.-p.  hour,  so  many  times  the  feed  water  to  pass  through 
the  condensers,  and  so  on,  whereas,  given  the  coal  contain 
14,000  B.Th.U.  per  pound,  there  will  be  30  per  cent,  lost  by 
radiation  or  up  the  chimney  and,  therefore,  9,800  units  will 
get  to  the  engines,  and  since  some  heat  is  converted  into  w<|rk 
—perhaps  5  to  10  per  cent. — there  maybe  as  many  as  9,000 
B.Th.U.  per  pound  of  coal  to  be  carried  off  in  the  cooling 
tanks,  and  this  is  then  the  figure  on  which  to  calculate  the 
air  supply.  The  water  is  merely  the  vehicle  of  the  heat 
and  is  hotter  or  colder  according  to  its  quantity,  but  the 
heat  units  remain  the  same. 

152 


HEAT 

The  Barometer. 

The  height  of  the  barometer  varies  slightly  with  the  lati- 
tude, though  hardly  sufficient  to  be  of  any  account  in  steam 
engineering  and,  indeed,  quite  insignificant  as  compared 
with  the  ordinary  weather  variations. 

A  mercury  column  will  stand  at  14-704  in  London,  14-6967 
=  1-0333  kilos,  per  cm.  at  Paris  and  14-686"  at  New  York. 
To  reduce  to  any  other  latitude  the  height  will  be  in  milli- 
metres— 

(1  +  0-00531  Sin.2  48°  50')    ,         JoOKA/ 

H  =  760  mm.  x  —  * where  48°  50 

(1  +  0-00531  Sin.2  L) 

is  the  latitude  of  Paris. 

Variation  of  altitude  is  serious.  At  any  elevation  =  R 
feet  above  sea-level  the  barometric  height  in  inches  will  be — 

H  =  60,000  (1-477  -  log.  R)  where 

1.477  =  log.  of  30  (inches). 

The  weight  of  a  cubic  foot  of  air  at  62°  F.  =  532-5  grains. 
When  moisture  saturated  the  weight  is  529  grains. 

The  specific  gravity  of  air  is  819  times  less  than  that  of 
water  and  13-146  cubic  feet  at  62°  =  1  Ib. 

The  Specific  heat  of  air  is  0-2375  at  constant  pressure 
and  0-1686  at  constant  volume. 

At  32°  F.  1  Ib.  of  air  measures  12-385  cubic  feet  and 
1  cubic  foot  =  0-08073  Ib.  One  litre  of  air  at  0°  C.  and 
760  mm.  pressure  weighs  1-292743  grams. 


153 


CHAPTER  XIX 
CONDENSING  APPARATUS 

condenser  of  a  steam  engine  is  a  contrivance  where- 
JL  by  the  atmospheric  pressure  is  removed  from  the 
exhaust  side  of  the  working  piston  in  order  that  the  mean 
effective  pressure  on  the  working  side  of  the  piston  may  be 
correspondingly  increased.  The  maximum  possible  increase 
of  effective  pressure  is  one  atmosphere  =  14-7  Ib.  per  square 
inch  at  the  level  of  the  sea.  Thus  if  a  non-condensing 
engine  with  a  given  rate  of  expansion  had  a  mean  pressure 
of  48  Ib.  the  addition  of  a  condenser,  producing  a  vacuum 
of  say  12  Ib.,  would  add  25  per  cent,  to  the  mean  pressure 
and  effect  a  corresponding  economy. 

The  mean  pressure  of  factory  engines  on  steady  duty  is 
about  40  to  45  Ib.  referred  to  the  final  cylinder.  About  a 
third  of  this  is  due  to  the  condenser,  or  say  14  Ib.  below 
the  back  pressure  line  of  a  non-condensing  engine.  The 

economy  due  to  the  condenser  is  thus to   or 

40-14         45-14 

say  35  to  31  per  cent.,  neglecting  other  modifying  conditions. 

Where  engines  work  with  a  poor  load  factor,  as  in  the 
case  of  small  and  moderate  electric  tramway  systems,  the 
mean  pressure  is  never  great  and  the  relative  importance 
of  the  steady  vacuum  is  proportionately  enhanced  and  tHe 
economy  to  be  derived  from  a  condenser  may  be  very  great 
—perhaps  40  or  45  per  cent. 

If  it  were  not  that  a  quantity  of  air  gains  entrance  to 
the  condenser  with  the  exhaust  steam  and  through  un- 
discovered leaks,  the  only  thing  necessary  to  secure  the 
maximum  possible  vacuum  would  be  to  carry  a  drain  pipe 

154 


CONDENSING   APPARATUS 

from  the  condenser  to  a  distance  of  34  feet  vertically  below 
it  and  allow  it  to  terminate  in  a  tank  of  water  or  with  a 
turned-up  end.  The  maximum  vacuum,  consistently  with 
the  water  temperature  would  then  be  secured.  But  air  is 
always  present  and  must  be  removed.  Hence  arose  the 
air  pump  for  taking  off  the  air. 


TABLEX  III. 

PROPERTIES  OF  Low  PRESSURE  STEAM. 


Lbs.  per  square  inch. 

Total  Heat 

in   1    1V»     f\f 

Specific 

Tempera- 
ture in 
Degrees 
Fahren- 
heit. 

in  l  lo.  oi 
Steam 
raised  from 
water  at  0°F. 
British 
Thermal 
Units. 

Weight  of 
1  cubic  foot 
of  Steam 
inlbs. 

Volume  of 
1  Ib.  weight 
of  Steam  in 
cubic  feet; 

Volume 
or  cubic  feet 
of  Steam 
from  one 
cubic  foot 
of  water. 

Equiva- 
lent 
Head  of 
Water. 
Ft. 

Total  or 
Absolute 
Pressure. 

Pressure 
on 
Gauge. 

1-15 

0-5 

14-2 

80 

1137-5 

•0013 

726-60" 

45307 

2-31 

1 

13-7 

102 

1145-0 

•0030 

330-36' 

20600 

4-62 

2 

12-7 

126 

1152-2 

•0058 

172-08 

10730 

6-93 

3 

11-7 

141 

1156-8 

[•0085 

117-52 

7327 

9-24 

4 

10-7 

153 

1160-1 

•0112 

89-62 

5589 

11-50 

5 

9-7 

162 

1163-0 

•0138 

72-66 

4530 

13-86 

6      |g 

8-7 

170 

1165-3 

•0163 

61-21 

3816 

16-17 

7 

7-7 

176 

1167-3 

•1089 

52-94 

3301 

18-48 

8 

o   1 

6-7 

182 

1169-2 

•0214 

46-69 

2911 

20-79 

Q 

-< 
> 

5-7 

188 

1170-8 

•0239 

41-79 

2606 

23-10 

10 

4-7 

193 

1172-3 

-0264 

37-84 

2360 

25-41 

11 

3-7 

197 

1173-7 

•0289 

34-62 

2157 

27-72 

12 

2-7 

202 

1175-0 

•0314 

31-88 

1988 

30-03 

13 

1-7 

205 

1176-2 

•0338 

29-27 

1844 

32-34 

14 

0-7 

209 

1177-3 

•0362 

27-61 

1721 

34-00 

14-7 

0 

212 

1178-1        -0380 

26-36 

1644 

34-60 

15 

0-3 

213 

1178-4 

-0387 

25-85 

1611 

46-20 

20 

5 

228 

1182-9 

•0507 

19-72 

1229 

The  Law  of  Mixed  Vapours. 

If  reference  is  made  to  the  annexed  Table  XIII.  of  the 
properties  of  saturated  steam  it  will  be  observed  that  a  pres- 
sure of  1  Ib.  absolute  accompanies  a  temperature  of  102°  F., 
which  therefore  corresponds  with  a  vacuum  of  13-7  Ib. 
or  27 '95  inches  of  mercury.  In  the  absence  of  air  this 
vacuum  would  be  secured  where  the  condenser  temperature 

155 


WATER    SOFTENING   AND    TREATMENT 

was  as  low  as  102°  F.,  for  water  vapour  at  102°  F.  cannot 
alone  exert  a  pressure  greater  than  1  Ib.  per  square  inch. 
By  the  law  of  mixed  vapours  enunciated  by  Dalton,  how- 
ever, the  pressure  in  a  space  containing  a  liquid  and  above 
that  liquid  is  the  pressure  of  the  vapour  proper  to  the 
temperature  of  the  liquid  plus  the  pressure  of  any  gas,  as 
air,  occupying  the  space,  such  pressure  being  what  would 
be  exerted  by  such  air  if  alone  in  the  space.  That  is  to  say, 
the  pressure  in  a  space  above  water  exerted  by  water  vapour 
is  a  function  of  the  temperature  and  a  given  weight  of  vapour 
must  always  be  present  in  a  given  volume,  irrespective  of 
how  much  air  is  made  to  enter  the  same  space. 

Thus,  a  vessel  of  one  cubic  foot  capacity  will  contain 
0-03797  Ib.  of  steam  at  212°  F.  and  one  atmosphere  pressure. 
A  cubic  foot  of  air  at  212°,  containing  0-080728  Ib.,  will 
exert  a  pressure  of  1-365  atmospheres. 

If,  therefore,  into  a  space  of  one  cubic  foot  there  be  placed 
this  weight  of  air  at  21 2°  F.  and  one  boundary  of  the  vessel 
be  water  at  212°  F.,  the  pressure  in  that  vessel  will  be  2-365 
atmospheres,  or  the  joint  pressure  of  the  air  and  water. 
It  is  very  usual  to  assume  that  water  vapour  will  condense 
if  pressure  be  increased,  but  this  is  not  so  where  the  increase 
of  pressure  is  produced  by  the  addition  of  a  gas  exerting  no 
appreciable  chemical  attraction  on  the  water.  In  other 
words  it  is  necessary,  says  Rankine,  to  molecular  equili- 
brium that  a  cubic  foot  of  space  at  21 2°  F.  should  contain 
0-03797  Ib.  of  water  vapour,  no  matter  how  much  other 
gas  be  present.  Similarly,  at  any  other  temperature  a 
cubic  foot  of  space  must  contain  that  weight  of  water  vapour 
proper  to  the  temperature  and  as  shown  in  the  tables  of 
saturated  steam. 

Thus,  if  p  is  the  pressure  of  saturation  of  the  steam  for  a 
given  temperature  T,  and  P  is  the  total  pressure  for  fe, 
mixture  of  the  vapour  and  a  gas,  as  air,  the  density  of  the 
gas  alone  in  that  space  is  less  than  its  density  at  the  pressure 

P— ?? 

P  in  the  ratio  -.  Thus,  in  a  space  at  50°  F.  and  atmo- 
spheric pressure  =  14-7  Ib.,  what  is  the  air  present  in  a  cubic 
foot  of  space  ? 

156 


CONDENSING   APPARATUS 

The  steam  pressure  at  50°  is  0*173  Ib.  Therefore  the  air 
pressure  will  be  14-7  -  0-173  =  14-527  Ib.  The  weight  of 
a  cubic  foot  of  air  at  50°  and  14-7  Ib.  pressure  is  - 

400.0 

0-080728  X        =  0-077885  Ib. 

50°  +461-2 

Whence  the  weight  of  air  actually  present  with  the  steam 
in  one  cubic  foot  will  be — 

0-077885  X  14'527  =  0-07698  Ib. 
14-7 

The  foregoing  point  has  been  considerably  elaborated 
because  the  law  teaches  us  that  air  present  in  a  condenser 
adds  to  the  pressure  and  diminishes  the  volume.  The 
amount  of  air  present  is  found  from  the  thermometer  and 
the  vacuum  gauge  thus.  If  the  pressure  of  water  vapour 
at  the  condenser  temperature  of  say  102°  is  1  Ib.,  and 
the  vacuum  gauge  reads  12-5  Ib.  while  the  barometer  reads 
14-5  Ib.,  then  the  total  pressure  P  is  2  Ib.,  and  as  1  Ib.  is 
the  pressure  of  the  water  vapour,  the  remainder  is  that  due 
to  the  air  =  1  Ib.  Consequently  there  must  be  air  present 
in  the  condenser  that  has  a  density  of  1  as  against  its 
external  density  of  14-5  Ib.  Knowing  then  the  density  of 
air  in  the  condenser,  we  can  calculate  how  much  is  drawn 
out  at  each  stroke  of  the  air  pump. 

In  a  tight  air  pump,  when  the  bucket  is  at  the  top  of  its 
stroke,  the  space  above  the  bucket  is  filled  with  water  at 
the  condenser  temperature.  There  is  no  air,  for  this  has  all 
passed  through  the  delivery  valve,  the  clearance  being 
water-filled.  When  the  bucket  descends  it  creates  a  vacuum 
between  itself  and  the  delivery  valve  as  good  as  can  exist 
in  presence  of  water  at  the  temperature  of  that  present. 
This  vacuum  will  be  better  than  that  in  the  condenser, 
which  contains  air,  so  that  when  communication  is  now 
established  between  air  pump  and  condenser,  the  superior 
pressure  in  the  latter  will  cause  some  of  its  contents  to  enter 
the  air  pump  to  establish  an  equilibrium  since  it  is  not 
possible  for  two  unequal  pressures  to  exist  in  connected 
spaces.  Assume  that  the  absolute  pressure  in  the  air  pump 

157 


WATER  SOFTENING  AND  TREATMENT 

is  one  half  that  in  the  condenser,  then  the  volume  of  vapour 
entering  the  condenser  will  be  only  about  one-half  the  air- 
pump  capacity,  for  the  vapour  already  existent  will  simply 
be  moved  up  to  the  top  end  of  the  barrel  as  the  further 
vapour  enters.  The  only  air  present  in  the  pump  will  be 
what  rushes  in  with  this  last  entering  vapour,  and  in  ordinary 
practice  the  volume  of  such  a  pump  as  the  Edwards 
will  therefore  be  halved  so  far  as  its  capacity  to  abstract 
air  is  concerned.  Probably  in  practice  the  inrush  of  water 
which  takes  place  in  these  pumps  carries  in  with  it  a  greater 
proportion  of  air  than  the  above  and  somewhat  improves 
the  pump  efficiency,  but  prima  facie  an  air  pump  with  a 
foot  valve  should  have  a  better  volumetric  efficiency  than 
a  pump  without  a  foot  valve,  for  the  foot  valve  pump  draws 
in  the  average  mixture  from  the  condenser.  It  suffers, 
however,  from  such  diminution  of  efficiency  as  is  repre- 
sented by  the  pressure  required  to  lift  the  foot  valves.  This 
need  not  necessarily  be  great. 

The  law  of  mixed  vapours  has  been  generally  neglected 
by  all  writers  on  condensation,  not  excepting  the  Author. 
It  is,  however,  not  now  desirable  that  this  point  should  be 
further  neglected  in  view  of  the  high  vacua  that  are  con- 
sidered desirable  for  steam  turbine  work.  The  subject  is 
further  touched  on  when  dealing  with  actual  air  pumps. 

Having  thus  far  dealt  with  the  question  of  condensation 
on  general  principles  we  may  now  turn  to  matters  of  more 
detail. 

The  Water   Required   for   Condensing  Steam. 

It  is  of  little  use,  of  course,  to  keep  a  condenser  very  cold 
when  much  air  gains  an  entrance,  and  at  no  time  is  it  desir- 
able to  reduce  its  temperature  unduly,  for  the  temperature 
of  the  condenser  approximates  the  temperature  of  t^e 
moisture  which  evaporates  in  the  cylinder  during  the 
exhaust  stroke  and  is  thus  a  measure  of  the  loss  due  to 
re-evaporation.  Moreover,  the  condenser  outlet  temperature 
is  the  initial  temperature  of  the  boiler  feed  water,  and  if 
the  condensed  steam  passes  to  the  feed  heater  or  economizer, 
it  ought  not  to  enter  this  latter  below  100°  F.  or  thereabouts. 

158 


CONDENSING   APPARATUS 

and  a  condenser  temperature  of  110°F.  or  100°  F.  should  be 
low  enough. 

To  calculate  how  much  water  is  required  for  condensing  a 
given  quantity  of  steam,  it  is  known  first  that  1  Ib.  of 
water  heated  1°  Fahr.  requires  one  unit  of  heat  = 
1  B.Th.U.  One  Ib.  of  exhaust  steam  at  ordinary  con- 
denser temperature  contains  about  1,150  B.Th.U.  above  0°. 
Of  the  total  steam  used  by  an  engine,  not  less  than  10  per 
cent,  will  pass  to  the  condenser  as  water.  Consequently, 
if  its  temperature  at  exhaust  is  let  us  say  200°  F.  and  the 
condenser  has  a  temperature  of  100°  F.,  the  water  will  lose 
100°  F.,  or  say  about  100  B.Th.U.  per  pound. 

Then  for  1  Ib.  of  feed  water  supplied  there  will  be 
T\yth  Ib.  of  water  cooled  to  100°  F.  =  10  B.Th.U.,  and  /^th 

Ib.  of  steam,  which  will  lose  ^Q^^  °^  \  ?  -  \  \    —    945 

B.Th.U.  The  total  heat  to  be  absorbed  will  be  945  B.Th.U. 
and  for  convenience  the  amount  may  be  taken  at  1,000 
B.Th.U.  per  Ib.  of  steam  used  or  feed  water  supplied. 
Considering  the  heat  lost  by  radiation,  it  is  likely  that  not 
more  than  900  B.Th.U.  really  remain  to  be  absorbed  in  the 
condenser,  so  that  the  figure  named  should  be  ample  for 
use  in  the  formula  below. 

Calling  R  =  the  ratio  of  condensing  water  to  feed  water. 

T  =  Condenser  discharge  temperature. 

t    =  temperature  of  circulating  or  injection  water. 

W  =  weight  of  circulating  or  injection  water. 

w  =  weight  of  feed  water. 

W         1000  _  T 

Then  R  =  -  -.     Thus  where  T  =  100°    and 

w  T  —  t. 


1000    _ 

t  =  50°  ;    R  =  -  =  18,  or  the  condensing    water 

100  —  50 

required  in  these  circumstances  is  eighteen  times  the  feed 
water.  In  practice  R  varies  from  20  to  50  and  even  more 
where  the  supply  of  water  is  warm,  as  from  an  insufficient 
pond  or  cooling  tower. 

1000  +  R  t 

The  condenser  temperature  will  be  T  =  -       -  . 

1  +  R 

159 


WATER    SOFTENING   AND    TREATMENT 

Capacity  of  Condensers. 

The  capacity  of  a  condenser  depends  to  some  extent  upon 
the  speed  of  the  air  pump.  It  must  be  of  such  volume  that 
the  pressure  of  accumulating  air  shall  not  be  a  serious  frac- 
tion of  the  condenser  mean  pressure  during  one  cycle  of  the 
air  pump. 

A  condenser  must  also  be  large  enough  to  accept  the 
volume  of  steam  from  the  cylinder  and  expose  it  to  sufficient 
surface  of  cold  tubes  or  of  water  spray  instantly  to  condense 
it. 

The  air  which  enters  a  condenser  may  come  in  to  the 
amount  of  5  per  cent,  of  the  volume  of  injection  water. 
This  air  only  enters  injection  condensers. 

Gland  leakage  accounts  for  about  five  times  the  above 
quantity.  The  total  volume  at  atmospheric  pressure  may 
thus  be  O30  of  the  volume  of  the  water.  Arrived  in  the 
condenser  the  air  expands  in  accordance  with  the  absolute 
pressure  therein.  In  practice  one  can  only  find  how  much 
air  is  present  when  we  know  the  pressure  and  temperature 
as  explained  earlier. 

Condenser  capacities  have  been  fixed  by  practical  expe- 
rience at  one-fourth  to  one-half  the  capacity  of  the  low- 
pressure  cylinders  they  serve.  When  of  surface  type  this 
does  not  include  the  volume  occupied  by  the  tubes. 

Varieties  of  Condensers. 

There  are  three  main  varieties  of  condenser — viz.,  Jet, 
Surface  and  Ejector. 

The  Jet  Condenser. — This  is  a  plain  vessel  which  admits 
steam  usually  at  the  top  and  water  is  injected  at  right  angles 
to  the  steam  entrance  and  is  sprayed  by  the  whirling  motion 
imparted  to  it  by  its  passage  through  the  injection  valve. 
The  base  of  the  condenser  (Fig.  32)  is  connected  with  the 
air  pump,  a  foot  valve  being  interposed  in  old  practice,  but 
now  usually  omitted. 

»>.;  A  jet  condenser  may  always  be  employed  if  a  soft  clean 
f  eed  is  available.     In  such  a  case  it  .is  good  practice  to  pass 

160 


CONDENSING   APPARATUS 

the  feed  water  through  a  small  surface  condenser  placed  in 
the  path  of  the  exhaust  steam  to  the  jet  condenser. 

The  Surface  Condenser. — This  is  intended  to  conserve  the 
condensed  steam  in  order  to  avoid  scale  in  the  boilers.  In 
its  usual  form  it  consists  of  a  cylindrical  vessel  closely  packed 
with  tubes  through  which  the  condensing  water  is  circulated. 
With  ample  surface  well  distributed  so  that  the  whole  tube 
surface  is  swept  by  the  steam  and  short  circuits  of  steam 
avoided  the  amount  of  circulating  water  should  not  be 
greater  than  that  called  for  by  jet  condensers.  More  is  often 
required,  but  the  mean  temperature  of  the  circulation  water 
will  be  low,  indicating  inefficient  tube  surface.  About  10  Ib. 
of  steam  per  hour  can  be  condensed  per  square  foot  of  tube 
surface.  The  indented  tube  of  Row  is  claimed  to  have 
double  this  efficiency  owing  to  the  turbulence  of  flow  through 
it  and  it  has  been  shown  by  Stanton1  that  better  results 
are  obtained  by  small  tubes  of  great  length  placed  vertically 
with  down-flowing  water,  owing  to  the  turbulent  flow  which 
Professor  Reynolds  shows  to  exist  when  the  velocity  of  flow 

p 

passes  a  certain  critical  rate  V,  where  V  = ,   where 

"847  D 

D  =  the  diameter  of  tube  in  feet  and  P  is  a  value  based  on 
the  temperature  Centigrade  =  t°  C.  P  =  (1  +  0-0336  £°  + 
0-000221  P)-\ 

Turbulent  flow  adds  greatly  to  heat  absorption  efficiency. 

Ordinary  condenser  tubes  are  from  f  to  J  inch  diameter 
and  J 0  inch  in  thickness,  but  it  is  suggested  that  diameters 
of  J  inch  and  f  inch  would  be  better. 

In  order  to  promote  efficiency  the  water  usually  makes 
two  passes  through  the  tubes.  The  steam  meets  first  the 
pipes  of  the  second  pass  and  finally  the  first  pass  tubes. 
Suitable  baffle  plates  are  applied  in  order  to  spread  the 
steam  throughout  the  body  of  the  condenser. 

It  is  quite  usual  to  pass  feed  water  through  a  small  section 
of  the  surface  condenser,  certain  tubes  being  set  apart  for 
this  purpose  so  as  to  encounter  the  exhaust  steam  fresh 
from  the  cylinder. 

1  Minutes  of  Proc.  I.C.E.,  vol.  cxxxvi.  part  2. 

M 


WATER    SOFTENING    AND    TREATMENT 

It  is  sometimes  the  case  that  steam  to  be  condensed  passes 
through  the  tubes,  the  water  surrounding  them.  Where 
the  water  supply  is  very  large  this  is  perhaps  the  better  way. 
It  is  the  practice  with  water  supply  companies,  who  thus 
make  use  of  the  whole  water  supply  as  circulating  water, 
passing  it  all  through  the  condensers. 

Mr.  R.  W.  Allen  finds  the  friction  of  water  through  smooth 
condenser  tubes  by  the  following  formula1— 

lv2 

Ji  =  f ,  where  h  =  head,  in  feet,  lost. 

d2g 

I  =  tube  length  in  inches. 

v  =  velocity  of  flow  in  feet  per  second. 

d  =  internal  tube  diameter  in  inches  and  /  is  a  coefficient 
which  appears  to  have  a  mean  value  of  0-024  for  rates  of 
discharge  of  from  3  to  11  gallons  per  minute. 

Condenser  tubes  being  of  brass  are  always  smooth  in- 
ternally and  when  used  with  salt  or  corrosive  water  they 
are  tinned  for  protection  against  corrosion. 

Messrs.  Allen  &  Co.  make  condensers  in  which  the  upper 
bank  of  tubes  in  a  horizontal  condenser  are  more  widely 
spaced  apart  than  the  lower  bank  tubes  in  order  better  to 
admit  steam  which  strikes  first  the  upper  bank  of  tubes. 
Another  method  of  arriving  at  the  same  end  is  by  omitting 
some  of  the  tubes  as  will  be  seen  illustrated  later.  They 
also  construct  a  condenser  in  which  the  lower  tubes  are 
immersed  in  the  condensed  steam,  which  is  thus  cooled  to  a 
minimum  temperature  and  a  better  air-pump  efficiency  is 
obtained,  as  described  under  the  head  of  vertical  condensers. 

The  Ejector  Condenser. — In  this  apparatus  the  energy  in 
the  exhaust  steam  is  made  to  produce  the  necessary  vacuum 
by  reason  of  the  velocity  of  flow  impressed  on  a  stream  of 
water. 

The  outflow  of  steam  is  governed  by  the  laws  of  fluid 
motion.  The  outflow  velocity  of  a  fluid  is  V  =  ^2  g  h 
where  g  =  gravity  =  32-2  h  =  head  in  feet  and  V  =  feet 
velocity  per  second.  For  steam  the  head  h  at  3  Ib.  pressure 
absolute  is  more  than  7,000  times  that  of  water. 

1  Minutes  of  Proc.  I.C.E.,  Session  1904-5. 
162 


CONDENSING    APPARATUS 

Thus,  if  the  pressure  difference  in  an  ejector  is  2  ]b.  or  say 
4-6  feet  of  water  head,  the  steam  head  is  4-6  x  7,330  =  33,718 
feet  and  V  =  1,472  feet. 

A  simple  formula  for  V  is  V  =  60  v/T  where  T  is  the 
absolute  temperature.  A  minimum  of  888  feet  per  second 
is  also  given  for  the  velocity  of  steam  into  a  pressure  less 
than  three-fifths  its  initial  pressure.  In  any  case  the  velo- 
city is  high  and  the  mean  velocity  of  a  combined  jet  of 
steam  and  water  will  depend  on  the  ratio  of  weights  of  water 
and  steam.  Thus,  assume  29  of  water  and  one  of  steam 
or  a  total  combined  jet  of  30,  then  the  velocity  will  be 
one-thirtieth  of  say  900  =  30  feet  per  second,  or  one-thirtieth 
of  say  1,200  =  40  feet  per  second,  velocities  corresponding 
with  a  pressure  of  6  and  10  f  Ib.  respectively.  With  less 
water  and  an  initial  water  velocity  the  combined  velocity 
will  often  be  such  as  to  produce  a  vacuum  of  26  inches  of 
mercury,  or  about  13  Ib.  This  represents  a  head  of  about 
30  feet  of  water  and  a  velocity  of  nearly  44  feet  per  second. 

It  is  therefore  advantageous  that  the  water  should  ap- 
proach a  condenser  at  the  maximum  velocity  and  that  it 
should  be  as  cold  as  possible  in  order  that  as  little  as  possible 
should  be  employed,  and  that  the  steam  energy  should  be 
utilized  in  adding  to  the  velocity  of  approach  and  not  in 
moving  the  water  from  a  state  of  rest.  Ejector  condensers 
work  best  when  the  water  flows  from  a  reservoir  above.  In 
practice  the  water  is  often  supplied  to  them  by  a  centrifugal 
pump. 

The  atmospheric  condenser  is  merely  a  special  case  of  the 
surface  condenser,  but  the  cooled  surface  is  exposed  to  the 
air  and  the  cooling  effect  is  sometimes  augmented  by  the 
flow  of  a  thin  film  of  water  over  the  surface  of  the  pipes. 
In  this  case  the  condenser  is  known  as  the  evaporative  con- 
denser because  the  steam  within  the  pipes  is  cooled  by  the 
abstraction  of  heat  necessary  to  permit  of  the  absorption  of 
the  external  film  of  water  by  the  passing  air.  An  evapora- 
tion of  1  Ib.  of  water  outside  the  pipes  will  absorb  the 
latent  heat  of  an  equal  weight  of  steam  inside  them.  An 
exposed  position,  as  on  a  roof,  is  best  for  these  atmospheric 
condensers. 

163 


WATER    SOFTENING    AND    TREATMENT 

Calculations. 

All  calculations  for  condensing  plant  should  be  based 
simply  on  the  thermal  units  to  be  dealt  with.  Statements 
of  horse-power  are  useless.  The  weight  of  steam  to  be  con- 
densed must  be  known  and  this  will  vary  from  as  little  as 
13  Ib.  per  kilowatt  hour  to  as  much  as  50  Ib.  according  to 
the  load  factor  of  the  running  plant.  As  stated  already, 
1,000  B.Th.TJ.  may  be  assumed  per  pound  of  steam  con- 
densed and  1  B.Th.U.  per  pound  of  water  raised  1°  F. 

General  Design. 

This  may  vary  much.  Large  modern  power  stations  are 
tending  very  much  in  the  direction  of  separate  units,  each 
main  engine  having  its  own  condenser  plant  as  well  as  its 
own  particular  set  of  boilers.  Thus  the  Chelsea  Power 
House  of  the  Metropolitan  District  Railway  of  London  is 
little  else  than  eight  distinct  one-engine  stations  housed 
under  a  single  roof,  each  of  the  5,500  kw.  turbines 
drawing  its  steam  from  eight  boilers  and  passing  it  on  to 
one  condenser.  There  are  thus  eight  turbines,  sixty-four 
boilers  and  eight  condensers  :  and  eight  air  pumps. 
Much  of  course  will  depend  on  the  size  of  a  station.  The 
condensing  plant  may  consist  of  fewer  units  than  the 
engines,  more  than  one  engine  exhausting  to  each  condenser. 
Or  each  engine  may  drive  its  own  air  pump  and  use 
a  common  condenser,  so  that  the  maximum  of  condenser 
area  is  always  in  use  and  each  engine  draws  off  its  own 
proportion  of  air. 

Again,  the  air  pumps  may  be  entirely  separate  from  the 
main  engines  and  may  be  driven  by  their  own  direct-acting 
steam  cylinder,  by  a  high-class  rotative  engine,  or  in  an 
electric  station  by  an  electric  motor.  There  is,  indeed,  no 
limit  to  the  permutations  and  combinations  that  may  jpe 
effected  and  good  reasons  can  be  found  for  or  against  any 
arrangement. 

Thus,  an  independent  air  pump  may  be  wastefully  over- 
driven to  conceal  air  leakages.  Needless  hardly  to  say,  air 
leakage  should  be  so  minimized  that  when  everything  is 
shut  down  the  condenser  vacuum  should  not  fall  3  Ib.  in 

164 


CONDENSING   APPARATUS 

an  hour.  Good  joint  rings  and  well  painted  vacuum  sur- 
faces and  fibrous  packing  to  vacuum  glands  can  be  made 
to  permit  of  this. 

A  common  air  pump,  other  conditions  being  good,  can,  on 
the  other  hand,  be  varied  in  speed  to  suit  the  number  of 
engines  at  work.  The  independent  air  pump  also  allows  of  the 
vacuum  being  pumped  up  before  the  main  engine  is  started. 

Where  steam-driven  independent  air  pumps  are  employed 
they  may  usefully  exhaust  to  the  intermediate  receiver  of  a 
main  engine. 

In  tramp  steamers,  which  have  the  most  economical  steam 
plant,  everything  is  driven  off  the  main  engine  and  it  is 
obviously  more  economical  to  drive  from  the  main  engine 
than  it  is  to  employ  numerous  auxiliaries. 

It  is  often  urged  that  auxiliaries  can  use  their  exhaust 
to  heat  the  feed,  but  this  is  a  partial  truth  only,  for  the 
economizer  or  flue  feed  heater  will  usually  supply  feed  water 
hotter  than  it  can  be  given  by  exhaust  steam  heating.  Where 
there  is  no  economizer  the  feed  pump  steam  may  thus  be  used. 

The  position  of  condensing  plant  is  generally  below  the 
main  engines  for  convenience  in  drainage  and  water  supply. 
The  injection  or  jet  condenser  will  draw  its  own  water  from 
a  depth  of  17  feet  as  a  rule  without  risk  of  failure.  It  is 
also  undesirable  to  raise  the  circulating  water  too  high  above 
supply  level  and  the  circulating  system  should  be  a  closed 
circuit,  so  that  the  only  duty  of  the  circulating  pump  should 
be  to  keep  the  water  moving,  since  the  descending  stream 
will  balance  the  ascending  stream.  Air  will  sometimes  lodge 
at  the  high  points  in  a  circulating  system  and  these  high 
points  may  be  all  piped  by  small  air  pipes  to  an  ascending 
main  carried  up  fully  36  feet  to  a  small  closed  tank  from 
which  the  air  is  drawn  off  to  the  air  pumps.  This  will  safe- 
guard the  centrifugal  pump  from  failure,  for  it  must  be  one 
of  the  trapped  points. 

In  large  stations  the  circulating  water  is  led  through  the 
station  in  a  large  pipe,  from  which  each  condenser  pump 
draws  its  supply  and  every  condenser  circuit  discharges  into 
another  parallel  pipe.  It  is  usual  to  provide  that  either 
pipe  can  be  used  alternatively  as  the  supply  or  the  discharge 

165 


WATER    SOFTENING   AND    TREATMENT 

main  in  order  to  overcome  any  trouble  with  silting  up,  especi- 
ally when  drawing  from  a  muddy  or  tidal  river,  the  silt  being 
driven  out  by  the  reversed  flow  at  times  of  low  tide. 

A  silted  pipe  may  be  cleared  by  passing  through  it  in  the 
direction  of  flow  a  large  wooden  ball  slightly  smaller  than 
the  pipe  bore.  The  ball  floats  in  the  full  pipe  and  the  rush 
of  water  past  the  narrow  crescent  beneath  it  sluices  forward 
all  mud.  Certain  silt  will  settle  so  firmly  as  not  to  be  moved 
by  the  ordinary  flow,  and  as  such  supply  pipes  must  be 
wholly  below  lowest  water  level,  silting  is  apt  to  be  very 
troublesome. 

When  an  air  pump  is  directly  driven  by  the  main  engine 
and  this  is  of  large  vertical  type,  there  is  no  better  style  of 
pump  than  the  vertical  driven  by  a  lever  of  the  first  order 
pivoted  on  the  back  standards  of  the  engine  and  driven  off 
the  cross-head.  To  shorten  the  height  necessary  the  air 
pump  may  have  a  trunk  bucket,  the  connecting  link  to  the 
driving  lever  being  pinned  to  the  bottom  of  the  trunk.  But 
ordinary  rods  and  glands  are  usually  available.  The  air 
pump  is  practically  of  the  type  of  Fig.  50,  but  with  a  closed 
top  for  delivery  of  the  water  except  at  sea,  or  with  surface 
condensing,  the  water  may  flow  down  to  a  well  to  supply  the 
feed  pumps,  or  to  be  removed  by  other  means.  In  the  old 
factory  beam  engine  the  air  pump  is  almost  invariably 
driven  off  the  inner  pin  of  the  parallel  motion  at  half  the 
stroke  of  the  steam  piston  or  thereabouts.  Some  large 
horizontal  engines  drive  the  air  pump  by  an  L  lever  from  the 
tail  rod  of  the  engine,  while  others  again  have  driven  an 
inclined  air  pump  off  the  crank  pin  by  a  long  diagonal  rod. 
Air  pumps  have  also  been  driven  by  large  eccentrics,  but  this 
cannot  be  regarded  as  a  very  satisfactory  method  and  the 
eccentrics  are  apt  to  run  hot. 

Exhaust  Pipes. 

An  exhaust  pipe  between  an  engine  and  a  condenser  must 
obviously  be  much  larger  than  the  steam  supply  pipe  because 
of  the  increased  bulk  of  the  steam. 

A  customary  rule  in  English  practice  is  to  make  the 
exhaust  pipe  twice  the  area  of  the  steam  pipe.  American 

166 


CONDENSING   APPARATUS 

practice  favours  a  ratio  of  3  to  2  only  in  area,  or  the  steam 
pipe  has  an  area  7  per  cent,  of  the  cylinder  and  the  exhaust 
pipe  of  10  per  cent. 

Whereas  steam  velocity  is  limited  to  100  feet  per  second, 
that  of  the  exhaust  may  be  upwards  of  200  feet  per  second 
according  to  Rankine.  But  looked  at  in  another  way  the 
density  of  high-pressure  steam  is  that  equal  to  a  volume  of 
2- 5  cubic  feet  per  pound.  At  atmospheric  pressure  the 
density  is  that  of  26-33  feet  per  pound  or  1  :  10,  and  at  con- 
denser pressure  it  is  more  nearly  1  :  100,  as  compared  with 
initial  steam.  We  know,  however,  that  the  velocity  of  flow 
of  exhaust  steam  is  very  great  indeed,  for  at  once  when  the 
exhaust  valve  opens  the  pressure  very  quickly  falls  to  that 
proper  to  the  condenser  temperature.  A  rule  for  velocity 
in  feet  per  second  is  V  =  60-2  T  where  T  is  the  absolute 
temperature  and  V  =  the  velocity  of  flow  into  a  vacuum. 
Steam  of  any  pressure  flowing  into  any  other  pressure  less 
than  three-fifths  the  initial  has  a  velocity  of  888  feet  per 
second.  Hence  the  weight  discharged  is  proportionate  to 
the  density,  and  the  weight  discharged  per  minute  may  be 
found  by  multiplying  the  area  of  pipe  in  square  inches  by 
370  times  the  weight  of  a  cubic  foot. 

Thus,  an  engine  of  6,000  horse-power  uses  12  Ib.  of  steam 
per  horse-power  hour,  or  1,200  Ib.  per  minute. 

Exhausted  at  3  Ib.  absolute  into  a  condenser  at  less  than 
fths  of  3  Ib.,  or  say  1-5  Ib.,  the  velocity  being  888,  the  area  in 
square  inches  will  be  found  from  the  foregoing  formula,  or 
W  =  370  x  A  x  D.  Now  D  for  3  Ib.  is  0-00853  Ib.,  whence 

A: 


370  x  D 
Now  W  =  1,200,  so  that 

A  =  =  380  —  22  inches  diameter. 

3-15 

In  brief,  the  area  of  an  exhaust  pipe  in  square  inches  may 
be  a  fourth  to  a  third  of  the  pounds  of  steam  used  per  minute. 
A  deficiency  of  area  will  increase  the  back  pressure  in  the 
cylinder  and  a  cold  condenser  will  help  to  keep  down  the 
pressure  in  this  to  less  than  three-fifths  the  cylinder  back 


WATER    SOFTENING   AND    TREATMENT 

pressure,  and  so  help  to  maintain  the  flow  velocity  of  888 
feet  per  second.  The  law  of  mixed  vapours  here  points  out 
unmistakably  the  importance  of  keeping  air  out  of  the 
condenser. 

Cooling  Surface. 

This  at  10  Ib.  of  steam  per  square  foot  per  hour  would 
amount  in  the  above  example  to  7,200  square  feet.  With 
|  tubes  the  approximate  external  area  is  1  square  foot  per 
4  feet  length  of  tube.  The  tube  length  must  therefore  be 
28,800  linear  feet. 

If  the  tubes  are  7  feet  long  there  will  be  4,111  tubes  in  all. 
The  area  of  a  f  tube  is  0-6  square  inch  and  the  equivalent 
area  reduced  for  effect  of  vena  contracta  is  0-36.  Then  4,111 
x  0-36  —  1480,  or  fully  10  square  feet.  This  is  so  great  an 
area  for  water  passage  that  it  is  obviously  possible  if  we 
desire  it  to  add  to  the  length  of  the  tubes  and  reduce  their 
diameter  and  number. 

The  actual  tube  area  is  2466-6  square  inches,  or  17  square 
feet. 

At  30  times  the  feed  water  the  amount  of  circulating  water 
is  nearly  10  cubic  feet  per  second,  so  that  the  velocity  of 
flow  is  under  8  inches  per  second. 

Taking  Professor  Reynolds'  rule  for  turbulent  flow  and 
assuming  the  water  to  have  a  temperature  of  30°  C.,  we  have 

V  =  — — —  and  P  =  (1  +  0-0336  T  +  0-000221  T)  ~J  . 
84-7  D 

Then  P  =  (1  +  1-008  +  0-199)  -1  =  0-45. 

Now  D  =  1  inch  =  0-073  feet.     Whence  V=  -^-  =  -073 

6-183 

feet  per  second  =  f  inch  per  second.  Turbulent  flow  is 
thus  assured. 

The  rule  is  applicable  to  vertical  tubes  with  down-flowing 
water  and  does  not  seem  to  have  much  connexion  with 
practice,  for  the  velocity  of  flow  can  hardly  ever  be  less  than 
that  which  gives  turbulent  flow  if  the  rule  is  correct. 

If  the  water  flows  downwards  in  the  tubes  the  steam 
should  flow  upwards.  It  is  usual  to  make  the  water  flow 
through  the  tubes  in  two  sections.  This  at  once  halves 
the  area  as  found  above  to  the  equivalent  of  5  square  feet 

1 68 


CONDENSING   APPARATUS 


31.     PRIMITIVE  IDEAL  BARO- 
METRIC CONDENSER. 


effective  or  8-5  actual  and  increases  the  velocity  to  16  inches 

per  second. 

Even  three  sections  of  tubes  are  sometimes  arranged  so 

that  the  steam  can  enter  at  the 

top  of  the  condenser  and   the 

condensed   water    can    be    led 

away    from    the    base.      More 

usually    condensers    are    hori- 
zontal, the  water  making  two 

passes   through  the  tubes  and 

the    steam    meeting    first   the 

hotter  water,  or,  as  before  said, 

even  a  feed  water  heater  nest 

of  tubes  through  which  the  feed 

passes  on  its  way  to  the  econo- 
mizer. 

Many   horizontal  condensers 

have   tubes  of  about    1J  inch 

diameter,  fitted  sometimes  with 

internal  pipes,  the  water  tube 

being  closed  at  one  end  and  the  inner  tube  serving  to 

carry  water  into  it,  the  water  returning  by  the  annular  space 

between  the  inner  and  outer  tubes.  Such  tubes  being  free 
at  one  end  do  not  suffer  expansion  stresses 
and  may  be  expanded  at  the  other  end  into 
tube  plates.  When  both  ends  are  fixed  in 
tube  plates  the  stresses  soon  cause  leakage, 
and  though  one  end  may  be  expanded  fast 
the  other  end  must  have  a  gland  and  pack- 
ing of  cotton  so  as  to  allow  slight  move- 
ment of  the  tube. 

Wooden  ferrules  are  sometimes  used  as 
packing.  One-half  the  tubes  may  be  fixed 
into  one  tube  plate  and  the  remainder  into 
the  other.  This  leaves  more  room  for  the 
packing  glands  or  permits  closer  nesting  of 
the  tubes. 
When  steam  enters  a  condenser  and  meets  the  surface  of 

closely  packed  tubes  the  space  between  the  tubes  is  not 

169 


S 


FIG.  32.    JET 
CONDENSER. 


WATER  SOFTENING  AND  TREATMENT 


FIG.  33.     SURFACE  BARO- 
METRIC CONDENSER. 


sufficient  to  allow  free  passage  of  the  steam  to  all  the  tube 
surface.  It  is  now  the  practice  to  omit  certain  tubes,  so 
that  gaps  are  left  in  the  external  wall 
of  tubes  by  which  the  exposed  wall- 
ing of  tubes  is  much  increased  and 
steam  is  taken  well  into  the  middle 
of  the  nests  of  tubes,  as  in  Fig.  38. 

The  various  condenser  systems  de- 
scribed are  shown  in  the  accompany- 
ing figures.  Fig.  31  is  the  first  idea 
of  a  barometric  condenser  B,  placed 
so  that  the  height  H  is  over  30  feet. 
Steam  enters  from  the  cylinder  C 
through  a  valve  E  and  water  enters 
from  R. 

TThis  arrangement  will  act  until  it 
-4J  becomes  full  of  air.     A  small  dry  air 

I  pump  is  required  to  make  it  a  con- 

tinuous success. 

The  plain  jet  condenser  is  that  in 
Fig.  32  and  is  simply  a  cast-iron  jar. 

Steam   enters  at  S,  water  at  W  and   the   air  pump   draws 
away  steam  and  water  from  the  base. 

A  barometric  con- 
denser may  be  ar- 
ranged on  the  surface 
principle,  as  in  Fig. 
33,  the  dry  air  pump 
serving  to  withdraw 
any  air  not  carried 
off  by  the  down-rush 
of  water. 

The  general  idea 
of  the  horizontal  sur- 
face condenser  is  that 

Of  Fig.  34,  where  the     FlG   34      HORIZONTAL  SURFACE  CONDENSER. 
condensed    steam    is 

drawn  off  by  a  feed  pump   and  the  air   by  a  separate  air 
pump,    which    may   also,    if    large,    be  used  to  draw    the 

170 


CONDENSING 


APPARATUS 

This  implies  special 


circulating  water  through   the   tubes, 
design. 

Incrustation. 

Condenser  tubes  are  apt  to  become  coated  with  scale  on 
the  water  side  in  process  of  time.  They  can  usually  be 
cleaned  by  circulating  through  them  a  current  of  water 
acidulated  by  hydrochloric  acid  in  order  to  dissolve  the  crust 
which  is  carbonate  of  lime.  The  acid  should  be  a  20  per 
cent,  solution  only,  or  even  less. 

Economy  of  Condensing. 

The  following  Table  XIV.  is  given  by  the  late  Charles  E. 
Emery,  Ph.D.,  to  show  the  economy  that  may  be  secured 
by  condensing,  according  to  the  class  of  steam  engine 
employed.  It  is  for  average  conditions  and  steady  loads.  For 
underloaded  engines,  as  in  a  traction  plant,  the  economy 
will  often  be  very  much  greater  than  given  in  the  table,  on 
account  of  the  very  low  mean  pressures  that  are  usual  in 
most  traction  engines. 


TABLE  XIV. 


TYPE  OF  ENGINE. 

Feed-water  per  Indicated  Horse-power 
per  hour. 

Per 

Cent. 
Gained 

by 

Condens- 
ing. 

Non-Condensing. 

Condensing. 

NAME. 

Probable 
Limits. 

Assumed 
for 
Compari- 

I  Assumed 
Probable  '        for 
Limits    j  Compari- 

Ib. 

Ib. 

Ib. 

Ib. 

Simple   High-speed     35  to  26 

33        25  to  19 

22 

33 

Simple     Low-speed     32  to  24 

29 

24  to  18 

20 

31 

Compound      High- 

speed       .      .      .      30  to  22 

26 

24  to  16 

20 

23 

Compound       Low- 

speed 

24 

20  to  12| 

18 

25 

Triple    High-speed 

27  to  21 

24 

23  to  14 

17 

29 

Triple  Low-speed   . 

~ 

" 

18  to  12J 

16 

— 

171 


WATER    SOFTENING   AND    TREATMENT 

Solubility  of  Gases  in  Water. 

The  volume  of  gas  that  will  dissolve  in  one  volume  of 
water  is  called  the  coefficient  of  absorption,  the  volume  of 
gas  being  measured  at  32°  F.  and  30  inches  barometer  (0°  C. 
and  760  mm.).  Bunsen's  table  of  solubility  coefficients  is 
given  below  for  a  few  gases  likely  to  occur  in  feed  water. 

TABLE  XV. 


Temperature: 

0°C. 
32°  F. 

5°C. 
41°  F. 

10°  C. 
50°  F. 

15°  C. 
59°  F. 

20°  C. 
68°  F. 

Hydrogen    . 

0-01930 

0-01930 

0-01930 

0-01930 

0-01930 

Oxygen 

0-04114 

0-03628 

-0-03250 

0-02989 

0-02838 

Nitrogen 

0-02035 

0-01794 

0-01607 

0-01478 

0-01403 

Air    .      .      .      .      . 

0-02475 

0-02179 

0-01953 

0-01795 

0-01704 

Carbonic  acid   . 

1-7967 

1-4497 

1-1847 

1-0020 

0-9014 

Carbonic  oxide   •    . 

0-03287 

0-02920 

0-02635 

0-02432 

0-02312 

Carburetted  hydro- 

gen, CH4        .      . 

0-05449 

0-04885 

0-04372 

0-03900 

0-03499 

Carburetted  hydro- 

gen, C2H4      .      . 

0-2563 

0-2153 

0-1837 

0-1615 

0-1488 

Sulphuretted  hydro- 

gen    .... 

4-3706 

3-9652 

!  3-5858 

3-2326 

2-9053 

Ammonia    . 

1049-6 

917-9 

j  812-8 

727-2 

654-0 

At  the  boiling-point  practically  all  gas  is  occluded.  The 
solubility  increases  in  proportion  with  the  pressure,  showing 
that  gases  are  soluble  by  volume  and  not  by  weight.  The 
above  table  contains  all  the  information  likely  to  be  needed 
in  practice,  and  shows  that  ordinarily  it  is  carbonic  acid  gas 
which  is  to  be  dealt  with,  but  that  in  sewage  or  other  badly 
polluted  water  there  may  be  large  volumes  of  sulphuretted 
hydrogen  in  the  injection  water,  such  as  is  so  much  used  in 
the  town  of  Oldham  for  example. 


172 


CHAPTER  XX 


AJR  CooLtR 


EXAMPLES  OF  CONDENSERS 

OF  actual  condensers  the  barometric  type  finds  its  prac- 
tical extension  in  Fig.  35,  which  shows  the  head  of  the 
Worthington  Central  Condenser.  Here  the  exhaust  steam 
enters  at  one  side 
and  the  water 
enters  on  the  op- 
posite side  and 
flows  past  the 
tubular  air  cooler 
and  is  sprayed 
by  a  special  noz- 
zle into  the  path 
of  the  steam. 
The  air  pipe  is 
brought  into  the 
centre  as  shown 
and  if  the  down- 
pipe  is  not  too 
large  the  falling 
water  will  carry 
with  it  much  of 
the  air  and  the 
apparatus  may 
work  without  an 
air  pump.  An 
air  pump  is  usu- 
ally added  to 
imp  rove  the 
vacuum.  Hence 
the  air  cooler.  Such  a  condenser  is  particularly  fitted  to 


FIG.  35. 


OPFNINQ  TO  TAIL  PIPE 
WOBTHINGTON   CONDENSER   HEAD. 


173 


WATER    SOFTENING    AND    TREATMENT 

deal  with  a  good  supply  of  water  falling  from  above.  The 
ejector  condenser  may  also  be  assisted  by  a  barometric 
discharge  or  gravity  pipe. 


The  Wheeler  Condenser. 

The  single-ended  condenser,  used  in  America  but  little 
employed  in  Great  Britain,  with  inner  pipes  and  double 
water  chambers  is  shown  in  Fig.  36,  where  a  combined  air 
and  circulating  pump  is  shown  attached  below  the  con- 


WaUt    OvJ.lc.1 


FIG.  36.     WHEELEB  CONDENSER. 


denser.  These  condensers  may  be  either  circular  or  rect- 
angular in  cross  section.  Note  the  baffle  plate  under  the 
steam  inlet  to  spread  the  steam.  The  air  and  circulating 
pumps  are  driven  by  a  central  steam  cylinder,  the  exhaust 
from  which  should  pass  into  the  intermediate  receiver  of  the 
main  engine  or  through  a  feed  heater,  if  either  course  is  open. 
There  is  an  objection  to  this  double- tube  design  in  the  cool- 
ing of  the  outgoing  water  by  the  ingoing  stream  and  vice 
versa,  and  the  single  tube  is  to  be  recommended  in  pre- 
ference. 

174 


EXAMPLES    OF    CONDENSERS 

Morton's  Ejector   Condenser, 

as  made  by  Ledward  &  Co.  is  shown  in  Fig.  37.  It  consists 
of  a  series  of  combining  cones  by  which  steam  enters  a  flow- 
ing stream  of  water  from  a  nozzle  above.  The  principle  of 
action  has  already  been  explained.  The  1J  inch  size  will 
condense  ordinarily  200  Ib.  of  steam  per  hour  and  the 
18  inch  size  as  much  as  36,000  lb.,  the  ratio  of  water  to 


FIG.  37.     EJECTOR  CONDENSER  (Ledward). 

steam  being  assumed  27  :  1,  the  power  to  pump  which  is 
considered  to  amount  only  to  about  3  per  cent,  of  the 
economy  due  to  the  condenser. 


Surface  Condenser  with  Through  Tubes. 

This  type  is  illustrated  in  Fig.  38  in  cross  section  for  the 
purpose  of  showing  the  rows  of  tubes  omitted  to  facilitate 

175 


WATER    SOFTENING    AND    TREATMENT 

entry  of  steam.  Here  the  steam  first  strikes  a  distributing 
perforated  baffle  plate,  and  is  subsequently  further  regulated 
by  other  baffle  plates.  The  illustration  is  from  a  design  by 
Isaac  Storey  &  Sons,  Ltd. 


FIG.  38.     CROSS  SECTION  OF  SURFACE  CONDENSER  (Isaac  Storey  &  Sons). 

The  Vertical  Condenser. 

In  Fig.  39  is  shown  the  arrangement  of  the  vertical  con- 
densers of  the  Yorkshire  Power  Station  at  Thornhill,  and  of 
the  Lancashire  Power  Station  at  Radcliffe.  Each  of  three 
condensers  is  intended  to  deal  with  37,000  Ib.  of  steam  per 
hour  and  a  vacuum  of  28  inches  is  sought  with  a  30-inch 
barometer.  * 

There  are  4,500  square  feet  of  cooling  surface  disposed 
in  solid  drawn  brass  tubes,  1  inch  external  diameter,  of  18 
S.W.G.,  and  12  feet  6  inches  between  tube  plates,  which  are 
of  1J  inch  rolled  brass.  It  may  be  noted  here  that  a  brass 
tube  plate  possesses  the  advantage  of  having  a  similar  co- 
efficient of  expansion  to  the  brass  tubes. 

176 


EXAMPLES    OF   CONDENSERS 

The  water  and  steam  run  in  counter  current  through  the 
condenser  and  each  makes  three  passes  through  the  full 
length  of  the  condenser. 

The  air  pumps  in  this  case  are  three-throw  Edwards 
pumps  15  inches  diameter,  8  inches  stroke  and  run  at  165 
to  170  r.p.m.,  with  brass  liners  and  buckets  and  rods  driven 
by  15  horse-power  direct-coupled  motors.  There  is  a  flanged 
coupling  between  the  motor  and  the  pump  shaft  with  three- 
sixteenths  clearance  between  the  faces. 

The  driving  pins  are  fixed  in  one  half  and  fit  into  clearance 
holes  in  the  other  half. 

Provision  is  made  to  circulate  forty-five  times  the  feed 
water  supply  at  a  temperature  not  exceeding  60°  F.,  with  a 
view  to  a  high  vacuum  for  the  turbines. 

This  high  vaccum  is  sought  in  another  way  by  the  device 
shown  in  Fig.  40,  which  is  a  cross  section  of  a  condenser  by 
G.  &  J.  Weir.  In  this  condenser  the  outlet  for  the  water  is  a 
bonneted  stand  pipe  A,  so  arranged  with  an  outer  sleeve  B 
and  cover  C  that  the  air  pump  always  draws  the  lowest 
water  from  the  condenser  and  the  accumulation  of  water 
extends  to  E  E  above  several  rows  of  tubes,  which  serve  to 
chill  the  water  on  its  way  to  the  air  pump.  Thus  any  vapour 
in  the  air  pump  can  only  exist  at  the  pressure  proper  to  the 
temperature  of  the  cooled  water,  and  since  there  cannot  be 
two  different  pressures  in  the  same  space  vapour  and  air 
rush  to  the  pump  to  restore  equilibrium.  The  vapour  con- 
denses and  the  rush  continues  until  equilibrium  is  estab- 
lished by  the  air.  There  is  thus  more  air  in  a  unit  space  in 
the  air  pump  than  in  the  condenser  and  the  pump  efficiency 
is  therefore  improved  and  the  condenser  is  better  depleted 
of  air. 

In  the  vertical  condenser  plant  above  described  there  are 
small  air  pipes  carried  from  the  top  of  the  condenser  and  of 
the  centrifugal  circulating  pumps  and  every  high  point 
where  air  might  lodge.  These  are  carried  to  a  closed  tank 
about  40  feet  high,  which  is  exhausted  by  a  special  pump. 
The  object  is  to  ensure  that  no  air  shall  lodge  in  any  of  the 
above  points  to  destroy  the  action  of  the  centrifugal  pumps 
or  otherwise  hamper  circulation. 

177  N 


WATER    SOFTENING   AND    TREATMENT 


178 


EXAMPLES    OF    CONDENSERS 


179 


WATER  SOFTENING  AND  TREATMENT 

In  Fig.  41  is  shown  the  vertical  single-flow  condenser 
built  by  James  Simpson  &  Co.,  Ltd.,  for  the  Underground 
Electric  Railways  of  London  and  installed  at  Lots  Road, 
Chelsea. 

Eight  of  these  condensers  have  been  built  and  fixed, 
each  having  a  cooling  surface  of  15,000  square  feet,  and 


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FIG.  40.     CROSS  SECTION  OF  HORIZONTAL  CONDENSER  SHOWING  WATER 

OUTLET. 

capable  of  dealing  with  a  normal  load  of  85,000  Ib.  of  steam 
per  hour. 

The  air  pumps  are  of  the  dry  vacuum  type,  and  have  a 
displacement  of  about  900  cubic  feet  per  minute. 

The  condensed  water  pumps  are  of  the  centrifugal  type 
and  each  is  capable  of  dealing  with  the  above  quantitjt  of 
steam. 

Each  of  the  eight  condensing  sets  is  independent  in  every 
way  of  the  others,  and  is  proportioned  to  deal  with  an  over- 
load of  about  50  per  cent. 

At  Fig.  4 la  is  shown  a  Vertical  Double-flow  Surface 
Condenser,  also  by  James  Simpson  &  Co.,  Ltd.  This  con- 

180 


NDENSERS 

denser  has  a  cooling  surface  of  5,400  square  feet,  and  is 
capable  of  dealing  with  about  50,000  Ib.  of  steam  per 
hour. 

From  the  arrangement  of  the  inlet  and  outlet  branches 
for  steam,  circulating  water,  and  air-pump  discharge,  it  will 


WA*H  OUT  BRANCH^     -*s  ^CoNOtNeco  WATCR  OUTLET. 

Ai<  FW>  SUCTION 

FIG.  41.     VERTICAL  SINGLE-FLOW  SURFACE  CONDENSEB. 

be  noticed  that  the  steam  passes  through  the  length  of  the 
condenser  twice,  viz.,  down  one  side  and  up  the  other. 

Air  pumps  of  the  dry  vacuum  type  are  used  in  connexion 
with  this  type  of  condenser,  so  that  the  vapours  and  the 
condensed  water  are  taken  out  separately. 

In  Fig.  416  is  shown  the  same  firm's  Vertical  Single-flow 
Surface  Condenser  suitable  for  muddy  circulating  water. 

181 


WATER  SOFTENING  AND  TREATMENT 

This  condenser  was  specially  designed  with  the  object  of 
using  very  dirty  circulating  water  carrying  considerable 
quantities  of  mud  and  leaves  :  special  means  have  been 
provided  for  arresting  this  matter  by  providing  a  large 
chamber  at  the  bottom  of  the  condenser,  to  act  as  a  settling 
chamber  ;  and  gratings  or  screens  to  arrest  any  floating 


CONDENSED  WATER  SUCTION     - 


FIG.  4lA.     VERTICAL  DOUBLE-FLOW  SURFACE  CONDENSER.        * 

substance,  while  the  pipe  connexions  are  arranged  in  such 
a  way  that  both  halves  of  the  condenser  can  be  worked  at 
the  same  time,  or  separately,  so  that  by  closing  down  one 
half  of  the  circulating  system  it  can  be  readily  cleaned, 
whilst  the  other  half  is  carrying  the  load  with  a  slightly 
reduced  efficiency. 

182 


EXAMPLES    OF   CONDENSERS 

This  condenser  is  capable  of  dealing  with  85,000  Ib.  of 
steam  per  hour,  with  the  circulating  water  at  a  temperature 
of  from  60  to  70  degrees. 

The  cooling  surface  provided  is  about  8,500  square  feet. 


WASH-OUT  VALVC*. 


FIG.  416. — VERTICAL  SINGLE-FLOW  SURFACE  CONDENSER,  SUITABLE  FOR 
MUDDY  CIRCULATING  WATER. 


FIG.  42.     EVAPORATIVE  CONDENSER  (Ledward).     SIDE  VIEW. 
184 


FIG.  42A.     EVAPORATIVE  CONDENSER.     END  VIEW. 
185 


WATER    SOFTENING   AND    TREATMENT 

The  Evaporative  Condenser. 

This  condenser  is  shown  in  Figs.  42,  42a,  and  consists  of  an 
arrangement  of  gilled  cast-iron  pipes  exposed  to  air  and  to 
films  of  water.  About  two-thirds  the  weight  of  steam  con- 
densed by  them  is  evaporated  on  their  outer  surfaces. 

It  appears  from  some  tests  made  by  Mr.  Longridge  that 
about  1J  to  2  Ib.  of  steam  may  be  condensed  per  square 
foot  of  surface  per  hour  with  an  attained  vacuum  of  24  inches. 

It  is  important  that  the  pipes  of  these  condensers  should 
be  free  from  blown  or  spongy  parts,  for  it  does  not  appear 
desirable  to  paint  them,  and  if  not  sound  they  would  admit 
air  too  freely. 

It  seems  to  the  Author  that  the  steam  should  preferably 
flow  upwards — counter-current  fashion — instead  of  as  shown, 
and  that  small  water  drains  should  be  carried  down  from 
some  of  the  end  bends  direct  to  the  air  pump.  Still  under 
ordinary  conditions,  with  the  steam  entering  at  the  upper 
end,  a  vacuum  of  24  inches  is  guaranteed  and  even  more  is 
often  secured. 

Such  a  condenser  as  shown  in  Fig.  42,  consisting  of  eighty 
corrugated  pipes,  is  capable  of  dealing  with  2,400  Ib.  of 
steam  per  hour.  The  total  cooling  surface  of  the  condenser 
is  2,400  square  feet,  and  for  its  efficient  working  it  is  necessary 
to  provide  200  gallons  =  2,000  Ib.  of  water  per  hour  to 
replace  the  cooling  water  lost  by  evaporation,  or  four-fifths 
only  of  the  weight  of  steam  used  by  the  engine. 

Counter  Current  Jet  Condenser. 

The  Balcke  condenser,  in  which  the  principle  of  counter 
current  is  adapted  to  a  jet  condenser  is  shown  in  Fig.  43. 
Here  the  water  is  removed  at  a  definite  rate  by  the  lowter 
pump  and  air  is  removed  by  the  upper  pump  from  the  top 
of  the  condenser.  By  means  of  a  float  the  volume  of  the 
injection  is  regulated  by  the  water  level  which  is  kept  uni- 
form. The  water  enters  by  way  of  a  circular  lip  to  the  upper 
water  channel  and  is  well  spread  by  perforated  diaphragms. 
Steam  enters  below  the  water  spreader  and  air  is  drawn  up 

1 86 


EXAMPLES    OF    CONDENSERS 

through  the  cold  water,  so  that  as  fully  as  possible  the  air  is 
freed  from  water  vapour  and  the  capacity  of  the  dry  air 
pump  is  utilized  to  its  fullest  practicable  extent. 


FIG.  43.     BALCKE'S  JET  CONDENSER. 

Feed  water  is  drawn  from  the  base  of  the  condenser  and 
the  remainder  drawn  out  by  the  wet  "  air  "  pump  is,  when 
necessary,  forced  by  that  over  the  cooling  towers. 

Counter  Current  Surface  Condenser. 

The  principle  of  counter  current  condensation  and  an 
assured  turbulence  of  flow  is  secured  in  the  condenser  shown 
in  Fig.  44,  which  is  that  of  the  Concentric  Condenser  Co. 

In  this  Concentric  Condenser  of  Bracket  a  series  of  alter- 
nately plain  and  corrugated  tubes  are  nested  one  inside  the 
other  and  held  between  gun-metal  heads,  in  which  are  a 
number  of  concentric  grooves  turned  to  fit  the  tube  ends. 
These  heads  are  so  cast  that  every  other  space  communicates 
with  the  steam  chamber  and  the  other  alternate  spaces  with 
the  water  chamber  in  the  heads.  A  special  cement,  which 
softens  only  the  first  time  it  is  heated,  renders  the  tube  ends 
tight  against  leakage.  Steam  passes  one  way  and  water 


MAIN  EXHAUST  INLET 


UR.  WATER 

DISCHARGE. 

FROM  ELEMENT'' 


EXHAUST-STEAM 

INCET 
TO  ELEMENT 


CIR.  WATER  INLET 
TO  ELEMENT 


MAIN  CIR.  WATEr 
DISCHARGE 


SPECIAL  EXPANSION 

JOINTS  WITHTUNION 

CONNECTIONS 


AiR  PUMP  SUCTION 

FROM  ELEMENT 


MAIN  AIR 
PUMP  SUCTION 


MAIN  CIR.  WATER  INLET 

FIG.  44.  BRACKET'S  CONCENTBIC  CONDENSER, 
1 88 


EXAMPLES    OF    CONDENSERS 

moves  through  the  alternate  tubes  in  opposite  directions. 
Thus,  each  annular  passage  has  one  plain  and  one  corrugated 
boundary  and  the  escaping  condensed  steam  is  reduced  to  a 
temperature  as  low  as  possible,  while  the  water  of  circulation 
escapes  as  hot  as  possible. 

Surface  or  Tubular  Condenser. 

At  Fig.  61  in  the  chapter  on  air  pumps  will  be  found 
illustrated  the  condenser  of  Pollitt  and  Wigzell,  which  is  an 
ordinary  tubular  condenser  through  which  the  circulating 
water  passes  twice,  the  second  pass  being  where  it  should  be 
nearest  the  hotter  or  steam  inlet  position. 

The  special  point  is  the  entry  of  the  steam  parallel  with 
but  above  the  tubes  and  by  a  sloping  inlet  cover  piece 
which  extends  the  full  length  of  the  tubes  and  serves  to  dis- 
tribute the  steam  from  end  to  end  of  these  without  short 
circuit  danger  to  the  final  outlet.  By  this  means  every  unit 
of  tube  surface  is  made  useful  and  efficient.  These  con- 
densers have  been  much  used  in  the  Yorkshire  woollen 
factories,  being  placed  behind  the  L.P.  cylinder  of  tandem 
engines.  The  air  pump  is  placed  in  the  base  of  the  con- 
denser, and  a  nearly  full  length  opening  is  left  below  the 
tube  surface  in  order  to  prevent  short  circuit.  The  degree  of 
vacuum  secured  is  very  good,  and  may  be  explained  by  the 
careful  well  considered  points  of  the  design. 

The  Atmospheric  Valve. 

An  important  detail  of  a  modern  plant  is  the  atmospheric 
automatic  exhaust  valve.  This  is  a  mushroom  valve  fitted 
with  a  balance  lever  and  opening  upwards.  In  case  of 
failure  of  a  condenser  to  act,  the  pressure  of  steam,  which 
would  rise  to  a  dangerous  degree  and  might  burst  a  cast-iron 
condenser  casing,  raises  the  atmospheric  valve  and  allows 
the  steam  to  escape  into  the  atmosphere.  These  valves,  of 
which  two  illustrations  are  given,  Fig.  45  of  the  valve  made 
by  Templer  &  Ranoe  of  Coventry,  and  Fig.  46  that  made  by 
Thomas  Walker  of  Tewkesbury,  should  have  an  oil  dashpot 
to  restrain  too  rapid  movement.  The  valve  should  have  a 

189 


WATER  SOFTENING  AND  TREATMENT 

drain  pipe  from  an  inch  or  two  above  the  level  of  its  lip  in 
order  to  seal  this  effectively  against  air  leakage.       There 


FIG.  45.     ATMOSPHERIC  VALVE. 
190 


EXAMPLES    OF    CONDENSERS 

should  also  be  a  glass  water  gauge  to  show  the  water  level, 
and  a  supply  pipe  to  keep  up  the  water  supply.  It  is  usual 
to  carry  the  atmospheric  exhaust  above  the  roof  of  the 
building. 

One  such  valve  is  applied  to  each  engine  sometimes, 
especially  when  of  large  size,  or  there  may  be  one  valve  for 


FIG.  46.     ATMOSPHERIC  VALVE  (T.  Walker). 


a  number  of  small  engines  when  these  exhaust  to  a  common 
condenser.  The  atmospheric  automatic  valve  may  be  re- 
placed simply  by  a  hand  or  motor-worked  shut  valve  which 
provides  merely  an  alternative  route  for  the  exhaust  steam. 
In  the  valve  of  W.  H.  Spencer  &  Co.  of  Hitchin,  Figs. 
47,  48,  hammering  is  guarded  against  by  the  peculiar  arrange- 

191 


WATER  SOFTENING  AND  TREATMENT 

ment  of  the  seating  shown   in   more  detail  in  Fig.  49.     It 
will  be  noticed  that  the  valve  must  rise  from  its  seat  a  dis- 


tance B  before  steam  can  pass,  and  the  annular  space  N 
forms  a  cushion  which  prevents  the  valve  from  hammering 

192 


EXAMPLES    OF    CONDENSERS 

on  the  seat.  The  seating  is  made  renewable.  The  balance 
weight  is  set  to  balance  the  valve  and  the  spindle.  The 
spring  is  used  to  regulate  the  valve,  and  is  normally  regu- 


JLJt 


FIG.  48.     SECTION  OF  ATMOSPHEKIC  VALVE  (W.  H.  Spencer). 


lated  so  that  when  the  valve  is  under  equal  pressure  on  each 
side  it  is  raised  by  the  spring  nearly  the  height  B.  It  thus 
lifts  promptly  as  soon  as  the  vacuum  is  broken,  but  the 


FIG.  49.     DETAIL  OF  SEATING  OF  ATMOSPHERIC  VALVE  (W.  H.  Spencer). 

spring  tension  is  easily  overcome  when  there  is  a  partial 
vacuum  under  so  large  a  valve,  which  is  then  pulled  down 
to  its  seat. 

193  o 


CHAPTER  XXI 


AIR  PUMPS 


THE  Air  Pump  is  essential  to  most  condensing  systems. 
The  old  type  of  air  pump,  as  fitted  to  jet  condensers 
of  Boulton  and  Watt  and  other  engine  builders,  was  a  pump 
of  the  type  of  Fig.  50,  but  with  flap  foot-valve  and  flap 
discharge- valve.  With  the  condenser  it  was  fully  im- 
mersed in  a  deep  tank.  The  bucket  also  had  a  pair  of  flap 
valves  opening  upwards  like  the  wings 
of  an  insect.  Hence  the  name  "  but- 
terfly "  valve.  All  modern  air  pumps 
are  merely  a  development  of  this 
original  air  pump. 

The  air  pump  is  only  necessary  to 
prevent  the  gradual  accumulation  of 
air  from  the  feed  water  and  from 
leakage,  that  would  ultimately  fill  the 
condenser  to  boiler  pressure. 

The  action  of  a  pump  is  as  follows: — 

Assume  that  its  capacity  is  one  half 
that  of  the  condenser.  Then  each 
stroke  of  the  pump  will  take  out  half 
the  vapour  contents  of  the  condenser, 
and  therefore  approximately  half  the 
air.  It  would  remove  exactly  half  the  air  were  it  not 
that  the  relief  of  pressure  and  abstraction  of  air  will  allow 
more  vapour  to  rise  from  the  water  and  this  might  get  to  the 
air  pump  instead  of  the  mixed  vapour.  Thus  apart  from 
this  the  rarefication  would  proceed  according  to  the  square 
of  the  number  of  strokes  But  each  stroke  of  the  pump 

194 


FIG.  50.     PLAIN  AIR 
PUMP. 

I 


AIR    PUMPS 

draws  out  more  water  vapour  and  less  air,  and  as  air  is 
always  entering  the  condenser,  the  time  arrives  when  the 
intake  of  the  pump  is  exactly  equivalent  to  the  inflow  of  the 
air,  and  this  marks  the  maximum  possible  vacuum. 

A  vacuum  can  never  be  better  than  that  proper  to  the 
water  temperature,  and  will  be  less  according  to  the  laws 
of  mixed  vapours,  see  Chapter  XIX. 

Every  cubic  foot  of  air  which  enters  the  condenser  ex- 
pands to  from  5  to  25  cubic  feet.  The  speed  and  capacity 
of  the  air  pump  have  an  effect  on  the  capacity  of  the  con- 
denser, for  the  air  pump  is  intermittent  in  action  and  the 
condenser,  if  very  small,  would  show  a  fluctuating  pressure 
with  each  stroke  of  the  pump.  Large  condensers  and  mul- 
tiple fast-running  pumps  thus  show  the  steadiest  vacuum 
gauge.  An  important  point  in  air  pump  design  is  to  arrange 
that  no  air  that  gets  above  the  bucket  shall  remain  undis- 
charged that  same  stroke.  As  perfect  a  vacuum  as  possible 
is  formed  above  the  descending  bucket,  and  the  space  is 
filled  by  mixed  vapour  from  the  condenser.  The  foot  valve 
prevented  the  back  flow  of  the  enclosed  volume  of  vapour 
under  the  bucket,  but  in  some  modern  pumps  there  is  no 
foot  valve,  and  obviously  the  space  above  the  bucket  is 
filled  by  vapour  rising  from  the  water  seal  upon  the  bucket. 
Compare  Fig.  50  with  Fig.  51  to  gain  a  clear  idea  of  the 
difference. 

In  the  type  of  Fig.  51,  or  Edwards  pump,  the  condenser 
pressure  is  that  of  the  vapour  and  of  the  air,  and  the  air- 
pump  pressure  is  that  of  the  vapour  only.  If  the  mixed 
vapour  pressure  is  two  parts  due  to  vapour  and  one  part  to 
air,  only  one-third  of  the  pump  barrel  will  be  apparently 
available  to  take  a  further  supply  from  the  condenser,  but, 
as  will  be  seen  later,  this  view  must  be  modified  by  other 
reasoning. 

Continuous  running  of  an  air  pump  without  the  addition 
of  further  air  or  warmth  to  the  condenser,  would  finally 
result  in  refrigeration  of  the  condenser  by  evaporation.  An 
air  pump  overrun  tends  to  cause  refrigeration  at  the  ex- 
pense of  wasted  power. 

The  theoretical  power  absorbed  by  an  air  pump  in 

195 


WATER  SOFTENING  AND  TREATMENT 

charging  air  is  that  represented  by  the  work  in  compressing 
and  delivering  the  air  to  and  at  atmospheric  pressure  and 
isothermally,  for  substantially  the  temperature  remains 
unchanged. 

Per  cubic  foot  of  free  air,  i.e.  air  at  atmospheric  pressure, 
this  work  is  given  in  foot  pounds  by  the  following  formula — 

W  =  Atfxhyp.  log.  -?-,  where 

*o 
W  =  foot  pounds  of  work,  t  =  absolute  temperature,  usually 


FIG.  51.     EDWARDS  Am  PUMP. 

about  560°  F.,  p=  atmospheric  pressure,  andP0  =  condenser 
pressure. 

A  is  approximately  =  4  or  the  constant  number  53-15  4- 
(13  +  or  the  number  of  cubic  feet  per  Ib.  of  air  at  the  tem- 
perature t). 

Thus  for  t  =  576°  ;  P0  =  1-5  Ib.  p  =  l5  Ib.,  we  have  log. 
P  _O.Q 


196 


AIR    PUMPS 

and  W  =  4  x  576-0  x  2-3  =  5,300  foot  pounds  or  about  one- 
sixth  of  a  horse-power  minute.  Power  is  also  absorbed  by 
the  discharge  of  water,  which  must  be  pushed  into  the 
atmospheric  pressure.  The  rest  of  the  power  absorbed  is 
friction. 

In  the  working  of  the  common  air  pump  with  a  through 
valve  in  the  bucket,  this  evidently  descends  in  a  condition 
of  equilibrium  on  its  two  faces  and  absorbs  no  power  beyond 
frictional  effect.  On  the  upstroke  it  is  exposed  to  con- 
denser pressure  below  it.  Above  it  the  space  is  continually 
more  restricted.  But  practically  the  space  above  the 
bucket  does  not  vary  its  temperature,  and  that  part  of  the 
pressure  due  to  water  vapour  will  remain  constant,  for  the 
restriction  of  the  space  will  simply  send  part  of  the  water 
vapour  into  solution  in  the  water  present  with  it.  If  there- 
fore the  vacuum  gauge  shows  2J  Ib.  pressure,  corresponding 
with  a  vacuum  of  12-2  Ib.  normally,  and  the  condenser 
temperature  corresponds  with  a  steam  pressure  of  1J  Ib., 
then  the  air  is  per  se  at  a  pressure  of  1  Ib.,  and  the  work  done 
by  the  bucket  will  be  that  represented  by  the  compression 
of  air  from  1  Ib.  pressure  at  the  condenser  temperature  up 
to  14-7  Ib.  or  one  atmosphere.  The  net  foot  Ib.  per  cubic 
foot  of  air  at  atmospheric  air  will  be  as  stated  above  = 

W  =  A*  x  hyp.  log.-?-. 

*• 


For  the  figures  named  t°  is  about  115°  +  461  =  576°  (see 
Table  I.)  p  =  14-7  and  P0  =  1. 

Per  pound  of  air  the  formula  becomes — 

W  =  53-15*  x  hyp.  log.  ~P-. 

*i 

For  pumps  of  the  Edwards  type  the  conditions  are  a  little 
different.  The  bucket  descends  against  the  constant  pres- 
sure of  the  air  in  the  condenser,  for  it  is  practically  exposed 
on  both  sides  to  the  pressure  of  the  vapour  of  water.  There 
is  no  serious  compression  of  air  below  the  bucket  owing  to 
the  large  relative  capacity  of  the  condenser.  Otherwise  the 
bucket  does  slightly  raise  the  condenser  pressure. 

On  its  ascent  the  bucket  is  exposed  to  exactly  the  same 

197 


WATER  SOFTENING  AND  TREATMENT 

conditions  as  those  stated  for  the  common  type  of  pump. 
In  other  words  we  may  consider  only  that  component  of 
pressure  difference  of  the  mixed  vapour  due  to  the  air  and 
consider  only  that  isothermal  conditions  prevail,  because  of 
the  effect  of  the  water  present  and  the  small  intensity  of  the 
maximum  pressure  dealt  with,  namely  one  atmosphere 
which  does  not  involve  great  heat  production  in  generating. 
It  is  thus  easy  to  see  that  the  work  of  driving  an  air  pump 
may  very  well  be  chiefly  made  up  of  friction,  and  that  where 
air  is  present  in  small  volumes  only,  a  friction-producing 
bucket  had  better  be  run  as  slowly  as  may  be  possible, 
whereas  with  a  grooved  ringless  bucket  there  is  no  friction 
and  a  better  speed  may  be  run  with  economy. 

The  volume  to  be  generated  by  an  air  pump  bucket 
should  not  be  less  than  0-75  cubic  feet  per  pound  of  steam 
dealt  with  by  the  condenser  plant.  Mr.  R.  W.  Allen1  has 
made  tests  with  as  little  air-pump  capacity  as  0-5  cubic  feet 
and  he  gives  0-6  cubic  foot  as  a  minimum. 

With  a  temperature  of  discharge  of  circulating  water 
96-5°  F.,  he  obtained  a  vacuum  of  26-91  inches  by  gauge, 
corresponding  with  27-18  inches  if  corrected  for  30-inch 
barometer.  The  vacuum  corresponding  with  the  tempera- 
ture of  air-pump  discharge — 110' 5°  F.,  is  27 -I".  The  vacuum 
efficiency  is  given  as  99-25  per  cent.,  being  the  ratio  of 
26-91  to  27-18  inches.  The  air  pump  generated  0-496  cubic 
feet  per  pound  of  steam  condensed,  but  there  was  perhaps 
special  air- tightness  in  this  case. 

Barometer. 

The  variations  of  the  barometer  either  by  variable  weather 
conditions  or  altitude  have  no  serious  effect  on  air-pump 
work  in  this  country,  but  at  high  altitudes  (see  Table  in 
Chapter  XXVI.)  the  pressure  of  the  air  is  seriously  less. 
Boiler  pressure  is  greater,  per  gauge,  with  higher  altitude 
because  the  air  pressure  is  reduced.  A  boiler  at  14-7  Ib. 
absolute  pressure  always  contains  water  at  212°  F.,  if  no  air 
be  present  in  it.  An  air  pump  has  therefore  less  to  do  when 
pushing  its  discharge  into  the  atmosphere. 

1  Minutes  of  Proc.  Inst.  C.E.,  Session  1904-5. 
198 


AIR    PUMPS 

There  is  less  to  be  gained  from  condensing  at  high  alti- 
tudes than  at  low.  The  same  size  of  condenser  is  required, 
indeed  it  must  be  larger,  and  the  only  credit  item  must  come 
in  the  fact  that  slightly  less  power  should  be  absorbed  in 
driving  the  air  pump,  and  there  should  be  less  air  to  deal 
with  both  from  the  injection  in  a  jet  condenser  and  from 
leakage  through  glands,  etc.,  owing  to  the  reduced  atmo- 
spheric pressure  which  tends  to  reduced  air  solution  and  to 
reduced  leakage. 

These  are  small  items,  and  generally  it  may  be  said  that 
condensing  provides  less  economy,  but  the  question  will 
scarcely  arise  on  which  this  need  be  considered,  for  even  so 
high  up  as  the  Rand,  S.A.,  the  atmospheric  pressure  is  still 
over  12  Ib. 

The  Air -Pump  Bucket. 

In  the  early  air  pumps  the  bucket  consisted  of  a  plain 
casting  like  a  thick  flanged  pulley,  the  space  between  the 
flanges  being  filled  with  blocks  of  spruce  pine  tightly  driven 
in  dry  and  turned  to  fit  the  barrel.  When  wetted  the 
bucket  became  a  tight  fit  in  the  barrel,  and  very  soon  it  wore 
easy  and  worked  quite  as  well  and  with  much  less  friction. 

In  other  cases  the  wood  was  replaced  by  greased  rope. 
Then  about  1870  the  metallic  pump  bucket  with  rings 
sprung  in  like  a  steam  piston  became  more  and  more  used. 
It  is  however  a  mistake  to  use  rings  in  a  wet  air  pump. 
They  are  a  frequent  cause  of  failure,  breaking  and  overriding, 
etc.  A  bucket  should  be  as  long,  or  nearly  so,  as  its  dia- 
meter, especially  in  small  sizes,  and  never  less  than  five  inches 
long.  In  ordinary  water  pumps  the  Author  makes  buckets 
about  four  inches  long,  plus  half  the  diameter. 

The  bucket  should  be  a  plain  cylinder  fitting  the  barrel 
closely.  Its  surface  should  be  cut  into  grooves  about  |  to 
iV  wide  by  ^  to  J  deep,  with  spaces  between  of  -£-  to  -jj .  Thus 
made  there  will  be  no  serious  leakage  nor  wear,  and  no  fric- 
tion. The  packing  of  a  pump  bucket  or  the  use  of  rings  will 
not  bear  reasoning  upon.  Indeed  it  is  absurd  to  suppose 
that  leakage  can  take  place  through  the  length  of  a  bucket 
with  its  score  or  more  of  eddy-forming  square- cut  grooves. 

199 


WATER  SOFTENING  AND  TREATMENT 

General  Forms  of  Air  Pumps. 

There  are  two  main  types  of  pump  in  respect  of  their 
action,  viz.,  bucket  pumps  and  plungers  or  displacers.  The 
bucket  pump  requires  no  further  special  description.  In 
the  displacement  pump  the  bucket  is  merely  a  solid  plunger, 
often  more  or  less  ogival  ended,  which  enters  upon  and  re- 
cedes from  the  space  volume  of  the  barrel  or  end  chambers. 

Whereas  pumps  work  best  perhaps  when  vertical,  they 
are  often  made  horizontal,  but  even  in  certain  horizontal 
pumps  the  real  surface  which  expels  air  is  the  surface  of 
water,  in  the  end  chambers  of  the  pump,  which  is  caused  to 
rise  and  fall  by  the  displacement  of  the  horizontally-moving 
plunger.  Pumps  are  made  single  or  double  acting,  and  in 
certain  forms  of  horizontal  pumps  it  becomes  necessary  to 
take  into  consideration  certain  effects  of  gravity  in  deter- 
mining the  movement  of  the  water  so  as  to  avoid  shock. 

The  various  points  can  perhaps  best  be  brought  forward 
in  the  explanation  of  the  several  pumps  employed  as  illus- 
trative examples. 


200 


CHAPTER  XXII 
TYPES  OF  AIR  PUMPS 

The   Edwards  Air  Pump. 

IN  this  pump  (Figs.  51,  52)  the  speed  is  high  and  the 
water  is  compelled  to  enter  the  pump  by  the  sudden 
blow  of  the  conically-pointed  bucket  striking  the  water 
collected  in  the  lower  chamber  and  impelling  it  round  the 
curved  passages  which  direct  it  through  the  ports  just 
opened  by  the  de- 
scent of  the  bucket 
past  them,  as  seen 
in  Fig.  52.  The 
descent  of  the 
bucket  in  a  space 
vacant  of  air  pro- 
duces, as  explained 
previously,  a  vac- 
uum above  the 
bucket  as  perfect  as 
the  water  tempera- 
ture will  allow. 
There  is  no  air 
effect,  and  when  the 
ports  are  open  the 
mixed  air  and  gas 
in  the  condenser  FlG-  5'2-  EDWARDS  AIR  PUMP. 

rush    in  to  fill  the 

vacancy.  The  volume  of  the  barrel  above  the  bucket  is 
thus  available  to  the  extent  of  the  absence  of  air  which  is 
present  in  the  condenser,  and  it  must  not  be  imagined  that 
the  full  volume  of  the  bucket  stroke  is  abstracted  at  each 
stroke. 

201 


WATER  SOFTENING  AND  TREATMENT 


When  applied  to  jet  condensers  the  speed  is  more  moderate, 
as  shown  by  the  annexed  table,  which  shows  the  effect  of 
the  larger  volume  of  water  introduced  with  the  jet  as  com- 
pared with  that  in  the  discharge  from  a  surface  condenser. 


Difference 

Type 
of 
Condenser. 

Revolu- 
tions  per 
Minute. 

Vacuum 
in 

Inches. 

Barometer 
in 
Inches. 

Tempera- 
ture of  Air 
Pump 
Discharge 
in  Degrees 
Fahrenheit. 

Pressure 
due  to 
Tempera- 
ture in 
Inches. 

between 
Vacuum 
obtained 
and  highest 
Vacuum 
theoretically 
possible     if 

no  air  present 

No.  (1; 

240 

30-2 

30-85 

65 

•619 

•03 

Surface. 

250 

29-6 

30-8 

83 

1-1 

-1 

No.  (2) 

375 

28 

30-45 

107 

2-369 

•081 

Surface. 

No.  (3) 

128 

28-25 

30 

88 

1-328 

•422 

Jet. 

128 

28-375 

30 

84 

1-169 

•456 

This  pump  is  very  commonly  made  with  three  barrels. 
Such  a  pump  with  three  14-inch  diameter  barrels  and  a 
stroke  of  12  inches  is  rated  for  45,000  Ib.  of  steam  per  hour 
from  a  surface  condenser  if  run  at  a  speed  of  150  r.p.m. 
This  rating  points  to  a  capacity  of  0-66  of  a  cubic  foot  per 
pound  of  feed  water,  calculated  of  course  on  one  working 
stroke  of  each  barrel  per  revolution. 

A  convenient  way  of  driving  these  pumps  is  by  an  electric 
motor  through  gearing  which  may  include  a  raw  hide  pinion, 
and  in  any  case  should  be  broad,  of  fairly  fine  pitch,  and 
with  teeth  not  above  half  the  pitch  in  length. 

In  Fig.  53  is  seen  a  combined  air  and  circulating  pump 
with  electric  drive,  as  arranged  by  the  Mirrlees  Watson  Co., 
and  in  Fig.  54  a  double-barrel  Edwards  air  pump  with  cir- 
culating pump  and  surface  condenser  complete  by  Isaac 
Storey  &  Sons,  Ltd.  * 

It  should  be  added  that  when  the  bucket  uncovers  the 
ports  to  the  condenser  and  mixed  vapour  rushes  into  the 
pump  barrel  to  equalize  pressure  therein  with  that  in  the 
condenser,  the  inrush  will  continue  until  either  the  port  is 
again  closed  or  the  vapour  mixture  in  the  barrel  becomes 
identical  with  that  in  the  condenser,  for  since  the  air  pump 

202 


TYPES    OF    AIR    PUMPS 


Fi«.  53.     ELECTRICALLY  DRIVEN  AIR  AND  CIRCULATING  PUMP  (Mirrlees 

Watson  Co.) 


FIG.  54.     DOUBLE   AIR   PUMP   AND  CIRCULATING  PUMP    ELECTRICALLY 
DRIVEN  (Isaac  Storey  &  Sons,  Ltd.) 

203 


WATER    SOFTENING   AND    TREATMENT 


contains  only  water  vapour  this  must  have  a  pressure  proper 
to  the  temperature.  But  when  it  is  exposed  to  the  higher 
pressure  of  the  condenser  it  is  compressed  into  smaller  space, 
and  it  is  not  possible  for  more  water  vapour  to  exist  in  such 
smaller  space.  The  law  of  molecular  equilibrium  forbids 
this.  Therefore  the  pure  unmixed  water  vapour  must  all 
condense  to  water,  and  the  pump  barrel  must  become  full 

of  the  same  ratio  of  mixed 
vapour  as  exists  in  the  con- 
denser. The  Edwards  and 
similar  classes  of  pumps  do, 
therefore,  work  at  full  effici- 
ency if  there  is  time  to  allow 
of  this  while  the  ports  are 
uncovered  by  the  bucket.  It 
is  all  a  question  of  rapidity  of 
condensation  of  water  vapour 
exposed  to  a  pressure  inconsis- 
tent with  the  law  of  molecular 
equilibrium,  see  Chapter  XIX. 
The  Brake  Horse  Power 
required  to  drive  these  pumps 
may  be  taken  as  1  h.p.  for 
every  5,000  gallons  per  hour 
raised  20  feet,  or  10,000  gallons 
raised  10  feet  and  so  on.  Pipe 
friction  must  be  added  extra. 
The  vertical  air  pump  of 
Davey  Paxman  &  Co.  is  shown 
in  Fig.  55.  It  is  double  acting 
and  draws  its  supply  through 
a  port  which  is  uncovered  by  the  bucket  at  each  stroke.  On 
the  upstroke  of  the  bucket,  discharge  takes  place  through 
the  top  discharge  valves.  On  the  down  stroke,  discharge 
takes  place  into  the  bucket  and  thence  through  the  central 
guide  plunger,  which  is  water  sealed  as  shown  plainly  in  the 
figure.  This  is  a  high-speed  pump  and  can  be  run  direct 
off  a  high-speed  engine,  the  14-inch  dia.  x  7-inch  stroke 
three-crank  pump  being  run  at  250  revs,  per  minute. 

204 


FIG.  55.     VERTICAL  AIR  PUMP 
(Davey  Paxman  &  Co.) 


TYPES    OF    AIR    PUMPS 


Rather  over  half  the  duty  is  done  by  the  upper  side  of  the 
bucket,  and  being  double  acting  the  bucket  diameter  need 
not  be  above  about  seven- tenths  that  of  a  single-acting 
pump. 

TABLE  XVI. 
SIZES  OF  CENTRIFUGAL  PUMPS  SUITABLE  FOB  EJECTOR  CONDENSERS. 


Diameter 
of  Suction 
and 
Discharge 
pipes  in  inches. 

Revolutions 
per  minute 
for  lifts 
of  30  feet. 

Water 
discharged 
per 
minute. 

Suitable 
for 
Led  ward'  s 
Condenser 
No. 

2 

1650 

68  galls. 

3  to  4 

3 

1372 

150  „ 

5  to  6 

4 

1372 

250  „ 

6  to  7 

5 

1000 

420  „ 

8  to  10 

6 

1000 

620  „ 

12 

7 

769 

850  „ 

12  to  14 

8 

796 

1100  „ 

14  to  16 

10 

686 

1900  „ 

18 

12 

686 

2500  „ 

20 

TABLE  XVII. 
CAPACITY  OF  EJECTORS. 


No. 
corresponding 

A  — 

Capacity 
Steam 

Condensing 
Water 

to 
diameter  of 
Exhaust  Pipe 
in  inches. 

Condensed 
per  hour. 
Lb. 

required  per 
hour. 
Gallons. 

1* 

200 

550 

2J 

400 

1100 

3 

800 

2200 

4 

1500 

4000 

5 

2000 

5500 

6 

3000 

8250 

7 

4000 

11000 

8 

6000 

16500 

10 

8000 

22000 

12 

12000 

33000 

14 

20000 

55000 

16 

28000 

77000 

18 

36000 

99000 

20 

48000 

132000 

22 

56000 

165000 

24 

66000 

198000 

205 


WATER    SOFTENING    AND    TREATMENT 

The  Ejector  Air  Pump. 

This,  already  referred  to  as  the  Ejector  Condenser  (Fig. 
37),  acts  by  the  conversion  of  the  molecular  kinetic  energy 
in  the  exhaust  steam  into  kinetic  mass  energy  of  water. 
The  jet  of  water  flows  into  the  vacuum  formed  in  the  com- 
bining head  (Fig.  56)  and  carries  with  it  the  air  present  with 
the  steam.  It  is  considered  best  to  allow  water  to  enter 


FIG.  56.     EJECTOR  CONDENSER  WITH  PUMP  (Ledward.) 

from  an  elevation  of  15  to  20  feet  or  to  connect  a  centrifugal 
pump  directly  to  the  ejector  so  as  to  have  a  closed  cycle  from 
the  water  supply  to  the  ejector  discharge. 

The  direct  connexion  of  a  pump  is  shown  in  Fig.  56,  and 
such  pumps  may  be  motor  driven.  Ordinary  centrifugal 
pumps  will  perform  as  per  the  annexed  Table  XVI.,  and  the 
general  dimensions  of  ejectors  are  given  in  the  Table  XVII., 

206 


TYPES    OF    AIR    PUMPS 

together  with  their  capacity  in  steam  condensed  calculated 
on  the  assumption  of  a  water  supply  at  60°  F.  For  warmer 
water  the  ejector  requires  to  be  correspondingly  larger. 
When  fixed  horizontally,  as  they  may  be,  the  steam  should 
enter  from  above,  and  the  water  supply  should  have  a 
velocity  equivalent  to  a  head  of  20  to  30  feet. 

The  Displacement  Pump  of  Hick  Hargreaves  Co. 

In  this  pump  (Fig.  57)  a  round-ended  solid  plunger  works 
in  a  barrel  so  connected  to  a  valve  chamber  that  the  plunger 
is  double  acting.  The  inlets  are  by  the  inclined  laterally 
placed  valves  which  open  inwards  and  downwards,  and  the 
outlet  valves  are  at  the  top  of  the  central  and  annular  outlet 
chambers.  It  will  be  noted 
that  this  pump  is  always  full 
of  water  and  air,  and  that  as 
the  air  enters  it  rises  at  once 
to  the  top  of  the  outlet  cham- 
bers under  the  valves  and  is 
the  first  to  be  expelled.  The 
outlet  valves  are  always 
drowned  and  therefore  air- 
sealed.  This  type  of  pump 
was  applied  to  the  3,000  h.-p. 
engines  of  Messrs.  Sassoon  of 
Bombay,  together  with  a  cir- 
culating pump  of  similar  type. 
The  diagrams  1  to  4  (Fig.  58) 
show  the  general  form  of  in- 
dicator diagrams  from  good 
air  pumps,  the  compression 
being  indicated  by  the  up- 
ward curve,  the  expulsion  to 
the  atmosphere  by  the  short 
horizontal  line  at  the  top  of 
the  diagrams,  and  the  return 
stroke  by  the  lower  curve. 
The  diagrams  teach  by  the 
length  of  the  level  portion  FIO  57.  DISPLACEMENT  AIR  PUMP. 

207 


WATER    SOFTENING    AND    TREATMENT 


a. 

o 


CM 

«• 


that  the  pump  is  delivering   during  about  -J-  to  ^V  °^  its 

travel,  No.  1  top  taking  in 
less  air  evidently  than  the 
bottom  side. 


The  Horizontal  Air  Pump. 

When  horizontal  air  pumps 
were  first  employed  they  often 
gave  poor  results.  This  was 
explained  by  Mr.  Longridge 
in  his  report  of  18881  as  due 
to  bad  design.  Thus  in  pumps 
of  the  type  of  Fig.  59  he  states 
that  the  velocity  of  the  water 
in  the  barrel  must  not  exceed 
that  due  to  the  head  measured 
from  the  bucket  centre  to  the 
water  surface  in  the  end  cham- 
bers. Proper  design  therefore 
includes  a  question  of  height 
of  end  chamber. 

These  pumps  have  been 
much  employed  tandem  with 
the  steam  cylinders,  and 
therefore  with  a  bucket  velo- 
city of  600  to  700  feet  per 
minute  as  a  mean  and  there- 
fore a  maximum  speed,  1*57 
times  this,  or  say  950  feet  per 
minute  in  a  given  case.  With 
square- ended  barrel  the  vena 
contracta  effect  adds  50  per 
cent,  to  the  water  velocity 
necessary  to  follow  the  bucket 
solidly.  Let  this  velocity  be 
put  down  roundly  at  25  feet 
per  second.  Then  since  V  = 


J 


o 

CO 


o- 


1  See  Annual  Report    1838,  Engine,  Boiler  and  Employers'  Liability 
Association,  Ltd. 

20% 


TYPES    OF    AIR    PUMPS 

8  v/H  and  V=  25  feet  we  have  v/H=fully  3  feet  and  H  = 

9  feet.     If  this  height  cannot  be  allowed,  then  the  velocity 
must  be  less.     It  can  be  kept  down  to  that  of  the  bucket  by 
flaring  out  the  barrel  ends  to  the  correct  conoidal  form  so 
that  V  shall  only  be  16  to  18  feet  per  second,  and  then  H 
becomes  4  to  5J  feet,  but  height  and  correct  entrance  are 
needed  to  keep  the  water  solidly  against  the  bucket  face, 
and  the  movement  of  the  water  thus  to  and  fro  so  rapidly 
means  considerable  stress  on  parts.     Obviously  the  water 
surfaces  in  the  end  chambers  simply  move  up  and  down  and 
are  the  real  acting  faces  of  the  bucket  in  expelling  air  and 
drawing  it  in  from  the  condenser. 


FIG.  59.     HOBIZONTAL  Am  PUMP. 

Generally  the  pump  as  shown  in  Fig.  59  is  useful  for  lower 
speeds  and  for  driving  by  direct. acting  steam  cylinders.  It 
then  forms  a  good  combination,  and  the  bucket,  being 
always  drowned,  is  airtight. 

Tail  Rod  Pump. 

The  high-speed  tail-rod  pump  by  Pollitt  &  Wigzell  (Fig. 
60)  is  of  different  design  from  the  foregoing  and  consists  of 
an  air-pump  barrel  standing  out  horizontally  in  the  base  of 
a  jet  condenser.  The  bucket  is  solid  and  uncovers  a  series 
of  ring  ports,  on  its  outward  course,  through  which  enter 
water  and  air  to  be  expelled  through  the  end  delivery  valves. 
The  water  about  the  pump  is  always  maintained  as  a  mini- 

209  p 


WATER    SOFTENING   AND    TREATMENT 


mum  quantity.  Though  made  for  long-stroke  engines  this 
arrangement  is  silent,  and  it  is  run  at  upwards  of  880  feet 
per  minute  and  to  as  many  as  150  revolutions.  When 
attached  to  a  surface  condenser  the  arrangement  is  that  of 
Fig.  61,  with  often  a  circulating  pump  in  combination. 
Here  the  circulating  pump  must  not  be  called  on  to  lift  its 
supply  too  far.  Say  that  the  minimum  speed  of  the  bucket 
is  V=  820  feet  per  second  in  a  particular  case.  Then  the 

equivalent  head  will 
be  6J  feet  or  V=20 
=8  /H.  If  the 
pump  ordinarily 
would  lift  its  water 
23J  feet  at  slow 
speed,  it  should  not 
be  required  to  lift 
more  than  23 J—  6J  = 
17  feet,  or  to  allow 
ample  effect,  say  14 
feet. 

0 wi  ng  to  the 
bucket  velocity  the 
water  pushed  before 
it  distributes  evenly 
over  the  bucket  face, 
and  in  the  air  pump 
this  ensures  that  the 
air  shall  first  be  ex- 
pelled through  the 
delivery  valves.  If 
run  at  a  slow  speed, 
the  water  would  col- 
lect on  the  lower  part  of  the  barrel  and  much  air  w\)uld 
remain  behind  to  vitiate  the  vacuum  on  the  return  stroke. 
Probably  this  explains  the  failure  of  slow-running  horizontal 
air  pumps  not  supplied  with  end-water  chambers  of  a  height 
sufficient  to  drown  the  bucket.  It  will  be  noted  that  the 
circulating  pump  in  Fig.  61  is  double  acting,  and  draws  its 
water  from  a  surrounding  casing. 

210 


FIG.  60.     HIGH-SPEED  TAIL-ROD  AIR  PUMP. 


TYPES    OF   AIR    PUMPS 

In  Fig.  62  the  jet  condenser  is  seen  combined  with 
a  steam-driven  horizontal  air  pump  with  flywheel.  This 
enables  the  steam  to  be  used  expansively.  Steam  enters  the 


condenser  round  the  water-inlet  valve,  and  is  drawn  into  the 
pump  from  below.  The  air  rises  directly  to  the  outlet 
valves  and  is  promptly  discharged. 

211 


212 


TYPES    OF    AIR    PUMPS 

Combined  Direct-driven  Air  Pumps. 

In  Fig.  63  is  shown  the  Worthington  Co.'s  direct  driven 
air  and  circulating  pump  with  tubular  surface  condenser. 
For  an  area  of  1,075  square  feet  of  surface  steam  cylinders 
of  6  and  10  inches  compound  tandem  type  are  arranged  on 
the  same  rod  as  lOJ-inch  air  pumps  and  lOJ-inch  circulating 
pumps.  The  stroke  of  all  is  10  inches,  and  the  duplex 
arrangement  is  adopted,  making  two  complete  sets  side  by 
side  of  the  above  details.  The  Author's  experience  of  such 


FIG.  63.     COMBINED  AIR  AND  CIRCULATING  PUMPS. 

pumps  with  flat  indiarubber  valves  is  that  frequently  the 
valves  cockle  up  and  the  pumps  fall  off  in  efficiency  or  refuse 
work  entirely.  Dermatine  valves  stand  much  better  than 
rubber.  These  pumps  are  always  fixed  below  the  condenser, 
which  is  of  the  usual  two-pass  type  as  regards  water.  The 
tubes  of  the  Worthington  condenser  are  flanged  and  held  in 
one  tube  plate  by  a  packing  ring  and  screwed  ferrule.  At 
the  other  end  they  are  packed  and  fitted  with  a  screwed 
gland. 

Compound  Air  Pumps. 

The  ratio  of  the  atmospheric  pressure  to  the  pressure  in  a 
good  condenser  is  very  high.     The  action  of  an  air  pump 

213 


WATER    SOFTENING   AND   TREATMENT 

drawing  from  a  cold  condenser  is  equivalent  to  that  of  an 
air  compressor  compressing  to  a  very  high  degree. 

Thus  if  atmospheric  pressure  is  14-7,  and  a  vacuum  of 
28  inches  is  secured,  the  absolute  pressure  of  which  is  0-944 
lb.,  this  represents  the  maximum  possible  vacuum  for  a 
temperature  of  100°  F. 

Then  14-7-0-944  =  13-576  lb.  In  this  case  there  could 
be  no  air  present.  But  suppose  with  a  temperature  of 
100°  F.  that  the  vacuum  was  only  27J  inches  or  1-189  lb., 
then  1-189—  0-944  =  0-245  lb.  unaccounted  for,  or  rather 
accounted  for  by  air  pressure.  Then  14-7-^0-245=60,  and 
the  air  pump  in  such  a  case  will  be  called  on  to  compress  the 
air  sixty  times  in  delivering  it  to  the  atmosphere. 

Ostensibly  because  of  the  theory  that  air  forms  a  blanket 
about  the  tubes  of  a  condenser,  the  supplementary  condenser 
of  Parsons  is  employed  for  the  Parsons  turbine.  Actually 
this  augmentor  is  a  form  of  compound  air  pump — the  addi- 
tion of  a  second  stage  such  as  would  be  naturally  applied 
were  an  air  compressor  required  to  compress  to  sixty  atmo- 
spheres. Let  it  be  supposed  that  by  means  of  the  augmentor 
the  air  is  gathered  from  the  condenser  and  condensed  from 
0-245  lb.  to  as  much  as  2-45  lb. — the  Author  has  no  figures 
showing  the  effect  of  the  augmentor — then  the  ordinary 
air  pump,  instead  of  compressing  sixty  times  will  be  called 
on  to  compress  only  six  times.  Fig.  64  shows  an  arrange- 
ment of  this  two-stage  air  pump.  It  will  be  observed  that 
the  condenser  is  slightly  inclined,  and  the  water-outlet  pipe 
is  cranked  below  the  indraught  power  of  the  regular  air 
pump,  thus  forming  an  air  trap.  On  the  left  a  steam  ejector 
draws  air  and  vapour  out  of  the  condenser  and  forces  them 
through  the  small  augmentor  condenser,  which  is  full  of 
water  tubes,  and  forward  to  the  intake  of  the  air-pump, 
which  is  thus  enabled  to  pick  up  at  each  stroke  as  many 
times  the  quantity  of  air  as  is  represented  by  the  ratio  of 
compression  performed  by  the  ejector.  The  steam  con- 
sumption of  this  steam  jet  is  said  to  be  1J  per  cent,  of  the 
total  steam  used  at  full  load  by  the  engine.  The  water 
vapour  present  in  the  augmentor  space  is  only  that  proper 
to  the  temperature.  The  increase  of  pressure  due  to  the 

214 


TYPES    OF   AIR   PUMPS 

augmentor  jet  simply  causes  the  water  vapour  to  condense 
until  only  so  much  is  present  as  satisfies  the  molecular 
equilibrium. 

It  is  said  that  the  effect  is  to  increase  the  pressure  at  the 
air  pump  to  about  26  inches,  when  the  condenser  vacuum 
is  27  J  to  28  inches,  that  is,  the  effect  of  the  jet  is  to  produce 
a  difference  of  1£  to  2  inches  or  0-736  to  0-982  Ib. 

If  this  effect  were  produced  with  reciprocating  engines 
having  a  mean  pressure  referred  to  thel.-p.  cy Under  of  even 
as  low  as  30  Ib.,  the  advantage  gained  would  be  less  than 
3  per  cent,  gross  and  only  1 J  per  cent.  nett.  The  circulating 
water  used  in  turbine  work  is  usually  large,  about  fifty-fold 


FIG.  64.     Two -STAGE  Am  PUMP  WITH  JET  AUGMENTOR. 

the  full  load  steam  consumption  in  place  of  an  ordinary 
thirty-fold.  An  average  of  0-4  per  cent,  of  the  total  steam 
is  used  up  in  the  circulation  of  so  much  water,  and  the 
vacuum  is  improved,  says  Mr.  Parsons,  |  to  1  inch,  which 
represents  4  to  5  per  cent,  gain  of  power  in  the  turbine. 
The  auxiliary  condenser  has  a  surface  one-twentieth  that  of 
the  main  condenser.  If  from  these  figures 1  the  air  pres- 
sure be  assumed  increased  even  four  times  by  the  steam 
augmentor,  the  actual  air  pump  is  rendered  so  many  times 
more  efficient,  but  the  paper  gives  no  temperatures  from 
which  any  reliable  data  can  be  abstracted  on  this  item. 

1  Journal  Inst.  C.E.,  vol.  xxiii.  pt.  4. 
215 


WATER    SOFTENING    AND    TREATMENT 

Without  a  knowledge  of  condenser  temperatures  it  is 
impossible  to  judge  the  efficiency  of  operation  or  of  the 
amount  of  air  present. 

A  form  of  compound  air  pump  is  that  arranged  with  the 
barometric  condenser  at  the  Manhattan  Power  Station, 
New  York.  Originally  fitted  with  ordinary  triple-barrel  air 
pumps  these  proved  unsatisfactory.  In  place  of  these 
pumps  a  rotatory  dry  air  pump  was  arranged  to  take  "  dry  " 
air  from  the  head  of  the  barometric  condenser,  no  attempt 
being  made  to  carry  off  the  air  in  the  water  column,  though 
some  is  thus  carried  off.  But  the  dry  rotating  air  pump 


FIG.  65.     ROTATIVE  Ant  PUMP  FOR  AUGMENTOB,  WOBK. 

compresses  the  air  somewhat  and  delivers  into  the  baro- 
metric discharge  pipe  in  small  bubbles,  which  are  carried 
away  to  the  descending  column  of  water. 

The  air  pump  is  simply  a  modified  Beales  gas  exhauster, 
and  consists  of  a  cylindrical  casing  containing  a  smaller 
rotating  cylinder  fitted  with  four  sliding  blades  pressed  oirt- 
wards  by  springs  against  the  inner  surface  of  the  casing,  as 
shown  in  Fig.  65.  Thus,  instead  of  the  air-pump  diagram 
being  like  the  full  diagram  A  in  Fig.  66,  it  becomes  truncated 
to  the  form  B.  The  difference  of  pressure  against  which 
the  rotating  exhauster  works  is  thus  reduced  to  one-third  of 
what  would  be  necessary  if  discharging  to  atmosphere. 

216 


TYPES    OF   AIR   PUMPS 

Hence  the  possibility  of  using  this  gas  exhauster  otherwise 
not  suitable  for  air-pump  work. 

Position  of  Condensers  and  Air  Pumps. 

Given  absolute  airtightness  there  appears  no  reason  why 
the  condensing  plant  should  not,  if  necessary,  be  placed  a 
considerable  distance  from  the  engine  if  circumstances  call 
for  this.  The  exhaust  pipe  should  be  larger  when  long. 
But  where  reasonably  practicable  the  condenser  should  be 
close  to  the  engine,  and  so  should  the  air  pump,  if  only  to 
reduce  the  area  of  parts  containing  pressures  below  the 
atmosphere.  A  long  exhaust  pipe,  especially  in  the  open 


FIG.  66.     AIR-PUMP  DIAGRAMS. 

air,  will  act  as  a  condenser  and  relieve  the  work  on  the  con- 
denser proper.  In  all  probability  the  poor  vacua  which 
attend  long  exhaust  pipes  arise  from  air  leakages  through 
badly  jointed  pipes  and  bad  castings,  especially  about  the 
chaplet  marks  of  horizontally  cast  pipes.  All  good  pipes 
should  be  vertically  cast  and  should  be  dipped  hot  into  tar 
and  pitch  mixture  and  kept  well  painted. 

Given  large  and  tight  exhaust  pipes,  there  seems  no  reason 
why  steam  should  not  be  carried  far  to  a  condenser  in  pre- 
ference to  pumping  a  large  weight  of  water  uphill  to  an 
engine,  as  is  done  at  the  Newcastle-on-Tyne  Manors  Power 
Station. 


217 


CHAPTER  XXIii 
CIRCULATING  PUMPS 

SOME  of  these  will  be  found  illustrated  with  air  pumps 
and  condensers,  as  in  Figs.  36,  39,  53,  54,  etc.  Gener- 
ally speaking,  if  not  driven  by  the  main  engine,  the  centri- 
fugal pump  is  the  best  and  cheapest  form  of  pump  for  lifting 
or  forcing  a  large  body  of  water  at  a  low  pressure  through  a 
condenser.  This  pump  is  most  conveniently  driven  by  an 
electric  motor,  which  like  the  pump  requires  to  run  at  a  high 
rate  of  rotation.  They  are  small  in  bulk  for  their  output. 
Centrifugal  pumps  are  rated  for  size  by  the  diameter  of  their 
inlet  and  discharge  pipes,  and  their  output  ratio  varies  about 
with  the  square  of  this  diameter.  Thus  while  a  5-inch  pump 
should  discharge  about  30,000  gallons  per  hour  under  certain 
conditions,  a  7-inch  under  similar  conditions  will  discharge 
nearly  50,000  gallons.  A  rule  for  output  is  thus  F  =  3D 2 
where  D  is  the  diameter  in  inches  and  F  =  cubic  feet  per 
minute.  The  diameter  of  the  rotating  fan  or  runner  is 
about  3D. 

With  a  foot  valve  and  a  temperature  about  52°  F.  the 
Author  has  run  a  5-inch  centrifugal  pump  and  discharged 
20,000  gallons  per  hour  with  a  suction  lift  of  over  30  feet 
below  the  pump.  The  water  supply  was  an  artesian  well, 
and  the  probability  is  that  there  was  little  free  gasHn  the 
water  and  the  vacuum  proper  to  a  temperature  of  52°  F.  is 
over  29J  inches  of  mercury,  or  less  than  half  a  foot  of  water 
head.  This  shows  the  effect  of  air  in  vitiating  a  vacuum 
and  the  advantage  of  its  absence  in  securing  maximum 
pump  efficiencies. 

Any  kind  of  water  pump  may  be  employed  for  circulating 

218 


CIRCULATING   PUMPS 


purposes.  That  of  Hick  Hargreaves,  shown  in  Fig.  67, 
resembles  their  air  pump  and  consists  of  an  ogival  double- 
headed  plunger  moving  to  and  fro  in  a  sleeve  between  two 
water  chambers.  It  will  be  observed  that  such  a  pump  may 
be  placed  horizontally  or  vertically.  The  illustration  is 


p 

Ik 

TZI 

J 

a 

1JO 

J 

>.  <, 
».% 

r^- 

1 

•-- 

"•'    T> 

FIG.  67.     DISPLACEMENT  CIR- 
CULATING PUMP. 


FIG.  68.     DISPLACEMENT  CIRCULAT 
ING  PUMP  (The  Pulsometer  Co.). 


from  a  vertical  pump,  and  the  sloping  upper  boundary  of  the 
discharge  chambers  should  be  noted  whereby  the  last 
particle  of  air  can  escape  through  the  discharge  valves,  and 
any  air  trap  is  avoided. 

The  Pulsometer  Co.  make  the  vertical  displacement  cir- 
culating pump  Fig.   68,  the  points  to  be  noted  being  the 

219 


WATER  SOFTENING  AND  TREATMENT 


pointed  ends  of  the  plunger  and  the  sloping  upper  bound- 
aries of  the  two  chambers,  so  made  to  facilitate  free  escape 
of  air  to  the  discharge  valves. 

Coefficient  of  Contraction. 

Experience  has  proved  that  the  amount  of  water  flowing 
out  of  an  orifice  under  a  given  head  is  not  to  be  found  simply 
by  multiplying  the  velocity  due  to  the  head  by  the  area. 

A  deduction  has  to  be  made  from  this  theoretical  duty 
owing  to  the  peculiar  contraction  of  area  of  a  jet.  A  cor- 
rective coefficient  is  required  to  allow  for  this  "  vena  con- 
tracta" 

This  coefficient  varies  with  the  head  and  with  the  form 
of  the  orifice.  Navier  gives  the  co-efficient  =  C  =  0*636  for 
orifices  in  thin  plates  and  0*62  for  circular  orifices  of  which 
the  diameter  lies  between  0*02  m.  and  0-16  m.,  or  say 
|  to  6J  inches  where  the  head  does  not  exceed  6-80  m. 
or  about  22  feet  4  inches.  C  =  0-62  for  a  rectangular  orifice 
of  which  the  minimum  length  is  between  0-2  and  0-16  m. 
and  the  breadth  is  more  than  twenty  times  less.  For  a  very 
short  conical  orifice  if  2(j)  is  the  angle  of  the  cone,  C  is  given 
by  Castel  as  follows. 


2« 

C. 

2* 

c. 

0-0° 

•829 

13-24° 

•946 

1-36 

•866 

14-28 

•941 

3-10 

•895 

16-36 

•938 

4-10 

•912 

19-28 

•924 

5-26 

•924 

21-00 

•918 

7-52 

•929 

23-00 

•913 

8-58 

•934 

29-58 

•896 

10-20 

•938 

40-20 

•869 

12-04 

•942 

48-50 

•847 

Navier    gives    C^l'OO  for    2<jf>  =  2 
2<f)  =  50°. 


°    and    C  =  0'93    for 


220 


Section  III 


FEED   HEATERS 
STAGE   HEATING 


221 


CHAPTER  XXIV 
FEED  HEATING 

THE  object  of  heating  the  feed  water  of  a  steam  boiler 
is  five-fold.  First,  it  effects  a  saving  of  heat  that 
would  otherwise  go  to  waste  in  exhaust  steam  or  exhaust 
gases  ;  secondly,  it  enables  a  given  boiler  to  produce  more 
steam,  and  may  thus  obviate  the  necessity  of  adding  to 
plant ;  thirdly,  it  saves  a  boiler  from  certain  stresses  and 
certain  forms  of  corrosion  to  feed  in  the  water  hot ;  fourthly, 
the  heating  of  feed  water  assists  it  to  deposit  some  of  its 
salts  prior  to  entering  the  boiler,  and  if  a  temperature  of 
boiling  is  reached,  the  C02  gas  which  holds  lime  carbonate 
in  suspension  is  driven  off  and  temporary  hardness  is 
removed  thereby.  And  finally,  there  is  reason  to  believe 
that  the  heat  transference  from  a  fire  to  water  on  the  other 
side  of  a  fire-heated  plate  is  facilitated  when  fully  hot  water 
alone  is  allowed  to  enter  a  boiler.  On  this  point  there  are 
strong  differences  of  opinion,  and  no  final  test  determinations. 

Fire-Heated  or  Flue-Feed  Heaters. 

Practically,  the  fire-heated  flue-feed  heater  is  confined 
to  that  type  which  makes  use  of  heat  in  the  waste  gases 
of  a  furnace,  and  this  type  has  become  practically  reduced 
to  a  single  form,  which  has  become  known  as  the  Green's 
Economizer.  This  apparatus  consists  of  a  number  of  cast- 
iron  pipes  9  feet  long  and  4^  inches  external  diameter, 
with  their  ends  turned  true  and  pressed  into  cast-iron  end 
or  header  boxes  bored  out  to  receive  them.  These  headers 
vary  in  length  from  that  sufficient  to  hold  4  pipes  up  to 

223 


WATER    SOFTENING   AND    TREATMENT 

as  many  as  12,  the  sections  thus  built  up  always  extending 
across  the  flue,  which  is  usually  enlarged  so  that  the  net 


FIG.  69.     CROSS  SECTION  OF  ECONOMIZER. 

area  between  the  tubes  shall  be  the  equivalent  of  the  cross 
section  of  the  flue  leading  to  the  economizer. 

These  sections  are  built  in  the  widened  flue  in  multiples 

224 


FEED    HEATING 

of  four.  Thus,  the  smallest  economizer  of  6  pipes  (Fig.  69) 
in  width  must  contain  a  total  of  24,  48,  72,  or  96  pipes  and 
so  on,  the  reason  for  this  being  that  scrapers  are  made  to 
move  up  and  down  the  pipes,  and  each  two  rows  of  scrapers 
are  carried  by  a  chain  over  a  wheel,  and  on  the  other  end 
of  the  chain  are  the  scrapers  of  two  other  rows  of  pipe. 
Where  the  width  of  an  economizer  is  considerable,  there 
are  two  lines  of  suspension  wheels.  These  wheels  carry 
also  a  worm  wheel  and  they  are  all  driven  by  worms  on 
a  lay  shaft,  which  is  automatically  reversed  in  rotation  by 
an  automatic  tumbler  clutch  connected  to  the  driver  of  a 
double  pair  of  bevel  wheels.  In  this  way  the  scrapers 
constantly  travel  up  and  down  the  length  of  the  pipes 
and  remove  soot  and  dust,  which  falls  into  the  chamber 
below  the  lower  boxes.  Ordinarily  the  pipes  are  set  7J 
inches  apart,  C  to  C,  along  the  headers,  and  the  headers 
are  8  inches  centre  to  centre  along  the  flues. 

A  very  usual  allowance  of  economizer  is  3  square  feet 
of  pipe  area  for  each  square  foot  of  grate  surface.  This 
about  doubles  the  heating  surface  of  the  Lancashire  boiler, 
and  represents  from  960  to  1,200  square  feet  per  boiler  of 
economizer  surface,  or  96  to  120  pipes,  according  to  the  size 
of  the  boiler.  In  cotton  factories  it  is  very  usual  to  allow 
4  pipes  for  each  ton  of  coal  burned  per  week. 

All  the  headers,  top  and  bottom,  are  connected  to  a 
multiple  flanged  pipe,  through  which  water  is  fed  in  or 
taken  off.  On  these  inlet  and  outlet  pipes  are  pockets  to 
hold  thermometers  and  blow-out  and  safety  valves  respect- 
ively. The  scraper  gear  is  driven  by  a  small  engine,  by 
a  belt  from  some  adjacent  shaft,  or  by  an  electric  motor. 
The  top  boxes  have  a  capped  opening  opposite  each  tube, 
with  caps  and  centre  bolts  and  cross  bars. 

Economizers  are  put  in  the  full  run  of  the  main  flue, 
but  there  is  a  by-pass  flue  to  pass  the  gas  in  case  of  repair 
or  cleaning  of  the  economizer.  When  more  than  twelve 
sections  are  joined  together,  the  connecting  pipes  are  fitted 
with  spring  bends  projecting  horizontally  to  allow  of 
differential  expansion  of  parts.  In  large  economizers  there 
may  be  two  divisions  in  series,  one  after  another,  the  water 

225  Q 


WATER    SOFTENING    AND    TREATMENT 

first  entering  that  division  nearer  to  the  chimney.  As 
water  enters  an  economizer  equally  freely  at  each  section 
box,  the  pipes  most  highly  heated  will  have  the  best  circu- 
lation and  do  most  work.  All  the  pipes  are  in  parallel,  so 
that  the  average  water  movement  is  very  slow,  and  the 
resistance  to  flow  is  practically  nil,  and  the  placing  of  one 


FIG.  70.     GREEN'S  ECONOMIZER,  SHOWING  PARTIAL  RETURN  TO  PUMP. 

apparatus  in  series  with  another  adds  very  little  more  to 
the  resistance. 

Economizers  must  not  be  fed  with  water  at  less  than 
90°  to  100°  F.,  since  this  will  cause  some  of  the  moisture 
to  condense  on  the  lower  boxes  and  lower  sixth  or  there- 
abouts of  the  pipe  length.  To  avoid  this  effect,  which  will 
speedily  destroy  an  economizer,  a  part  of  the  discharged 
hot  water  is  returned  by  a  small  pipe  to  the  feed  pump 
suction,  and  serves  to  heat  the  feed  to  100°  F.  and  stop 

226 


FEED    HEATING 

further  condensation.     Otherwise  the  discharge  of  a  con- 
denser will  usually  be  hot  enough  to  serve  these  ends. 

This  is  seen  in  Fig.  70,  which  shows  a  Green's  Economizer 
and  its  by-pass  flue  as  arranged  in  a  very  usual  way  with 


FIG.  71.     GREEN'S  ECONOMIZER,  SHOWING  INITIAL  WARMING  SECTION. 

Lancashire  boilers.  Messrs.  Green  also  employ  the  method 
of  Fig.  71,  which  shows  a  general  plan  and  elevation  of  the 
pipes  and  side  or  soot  doors  for  inspecting  purposes.  The 
four  sections  of  pipes  next  the  chimney  are  independent  of 
the  remainder,  being  fed  with  water  in  their  top  boxes. 

227 


WATER    SOFTENING    AND    TREATMENT 

The  course  of  the  water  is  downwards,  arid  from  the  bottom 
boxes  it  passes  to  the  other  pipes  in  the  usual  way. 

Even  if  fed  with  cold  water  only  the  four  first  sections 
would  suffer  any  corrosion,  and  in  this  way  the  whole  of 
a  few  pipes  may  be  rusted  away  instead  of  a  sixth  part  of 
all  the  pipes,  which  would  be  as  surely  useless  as  if  wholly 
corroded.  Only  four  pipes  would  be  renewed  where  per- 
haps twenty-four  would  otherwise  require  renewal.  It  is, 


FIG.  72.     ECONOMIZER  WITH  INTERNAL  SCRAPERS. 

however,  a  simple  matter  with  cold  feed  to  adopt  £he 
method  of  Fig.  70,  and  return  some  of  the  hot  water  to 
the  feed  pump. 

Thus  B  is  the  pump  drawing  its  supply  by  the  pipe  D 
and  delivering  as  shown  by  the  arrows  to  the  economizer, 
whence  the  heated  water  travels  by  the  pipe  C  to  the 
boilers.  A  small  pipe  A  abstracts  a  portion  of  the  water 
from  C  and  redelivers  it  to  the  pump  section  D,  by  which 

228 


FEED    HEATING 

means  the  whole  of  the  feed  water  is  delivered  to  the 
economizer  at  a  temperature  above  90°  or  100°  F.,  the 
amount  of  returned  water  being  arranged  to  give  this 
temperature. 

If  hard  water  is  used  the  pipes  of  an  economizer  will 
gradually  choke  with  scale.  They  are  then  bored  out  by 
a  special  portable  set  of  multiple  boring  bars. 

In  Roberts'  economizer  (Fig.  72)  each  tube  has  an  internal 
revolving  scraper  in  constant  rotation  to  remove  scale  as 
rapidly  as  it  is  formed.  This  is  shown  in  Fig.  72.  The 
scrapers  are  driven  by  worm  wheels  with  shafts  in  each 
top  header  entering  through  stuffing  boxes.  A  standard 
economizer  has  10  square  feet  of  surface  per  pipe,  weighs 
280  Ib.  per  pipe,  and  holds  6J  gallons  per  pipe.  Experi- 
ment has  shown  that  there  is  no  difference  in  the  efficiency 
of  an  economizer  whether  it  be  arranged  for  the  pipes  to 
be  all  in  series  with  each  other  or  all  in  parallel,  but  when 
in  series  the  resistance  to  flow  may  be  much  increased. 
The  following  table  (XVIII.)  shows  the  approximate  saving 
due  to  each  degree  of  temperature  increase  at  different 
temperatures,  the  differences  down  the  columns  arising 
from  the  difference  of  specific  heat  of  water,  which  is  greater 
at  the  higher  temperatures,  and  a  degree  of  temperature 
represents  more  heat  per  Ib.  of  water. 

In  the  annexed  table  (XVIII.)  the  percentage  of  saving 
due  to  feed  heating  is  shown  for  a  steam  pressure  of  60  Ib. 

In  general  the  gases  are  not  to  be  cooled  below  350°  F., 
for  the  sake  of  the  chimney  draught,  but  there  is  no  limit 
to  the  cooling  that  may  be  allowed  for  fan  draughts.  The 
economy  of  feed  heating  is  measured  by  the  ratio  of  the 
heat  added  to  the  feed-  water,  and  the  total  heat  in  the  steam 
above  initial  feed  water  temperature. 

Thus  the  total  heat  in  a  pound  of  steam  will  be  about 
1,100  B.Th.U.,  and  if  140°  F.  of  temperature  is  added  to 
the  feed,  this  is  very  nearly  equal  to  140  B.Th.U.  Then 

1,100—140       96 

=  TT^=  0'873,  showing  an  economy  of  100  -  87*3 


=  12-7  per  cent.     The  following  table  (XIX.)  is  calculated 
on  this  basis  for  a  pressure  of  60  Ib. 

229 


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231 


WATER    SOFTENING   AND    TREATMENT 


The  following  table  (XX.)  shows  figures  obtained  by  the 
Author  and  other  observers  of  the  performances  of  econo- 
mizers : — 

TABLE  XX. 


Gas  Temperature. 

Water  Temperature 

No.  of  Pipes 

Total  Number 

per  Boiler. 

of  Pipes. 

Inlet. 

Outlet. 

Fall. 

Inlet. 

Outlet. 

Rise. 

32 

600 

480 

120 

96 

240 

144 

64 

80 

580 

290 

290 

98 

215 

117 

320 

72 

630 

520 

110 

93 

217 

124 

144 

75 

640 

460 

180 

90 

225 

135 

224 

52 

570 

388 

182 

107 

170 

[,63 

208 

72 

560 

360 

200 

54 

204 

150 

72 

Average  of  a  large  number  of  economizers,   including  those 
above : — 


557    1    381 

176 

93 

202 

109 

The  maximum  recorded  rise  of  feed  temperature  noted 
in  one  year's  inspections  of  economizers  by  the  Manchester 
Steam  Users'  Association,  was  187°  F.,  but  higher  figures  are 
no  doubt  often  obtained  where  boilers  are  more  severely 
worked. 

Mr.  M.  Longridge  has  shown  that  the  weight  of  feed 
water  per  hour  multiplied  by  the  temperature  rise  and 
divided  by  the  square  feet  of  economizer  area,  gave  an 
average  rate  of  heat  transmission  of  876  to  1,095  B.Th.U. 
per  square  foot  per  hour,  whence  he  deduced  that  with  an 
economizer  surface  equal  to  the  boiler  heating  surface  an 
average  heat  transmission  of  1,000  to  1,300  B.Th.U.  per 
hour  per  square  foot  may  be  looked  for  when  £  to  1  Ib.  of 
coal  per  hour  is  burned  per  square  foot  of  boiler  heJting 
surface. 

The  following  table  (XXI.)  shows  the  general  dimensions 
of  the  chamber  space  of  economizers  6  to  10  pipes  in  width 
and  up  to  48  sections  in  length.  The  chamber  below  the 
bottom  boxes  should  be  30  to  36  inches  deep  for  soot  and 
dust  accumulation.  One  side  of  the  economizer  chamber 

232 


FEED    HEATING 

is  made  with  a  passage  for  the  inspector.  This  passage 
must  be  closed  at  each  end  by  deflectors  or  dampers,  to 
prevent  short  circuit  of  the  draught.  No  scrapers  are 
needed  if  combustion  is  perfect,  but  ordinary  furnaces 
produce  much  smoke,  and  soot  rapidly  settles  on  the  pipes, 
and  these  sometimes  become  covered  with  a  tenacious 
sticky  tarry  deposit.  This  can  only  be  removed  by  burning 
off.  To  do  this  the  economizer  is  run  dry  and  the  hot 
gases  are  passed  through  for  several  hours.  This  operation 
requires  very  careful  carrying  out,  or  the  economizer  may 
be  overheated  or  injured.  As  with  boilers,  the  dampers 
of  an  economizer  are  best  of  swivel  type,  thus  preventing 
the  large  air  leakage  through  the  slot  of  slide  dampers. 


TABLE  XXI. 
ECONOMIZER  CHAMBER  SPACE. 

Width  of  Chamber. 

For  4  pipes 3  ft.  4  in.   ) 

,,6       „          4    „    8    „     [If  with  side  Deflectors, 

,,8       „          6    „    0    „  add  9  inches. 

„   10       „          7    „    4    „    j 

Lengths. 


No.  of  Sections  or  Rows 


s 


12 


16 


20 


24 


Length  of  Economizer    . 

ft.  in. 
4  10 

ft.    in. 
7     3 

ft.    in. 
9     8 

ft.  in. 
12  1 

ft.  in. 
14  6 

No.  of  Sections  or  Rows 

28 

32 

36 

40 

48 

Length  of  Economizer    . 

ft.    in. 
16  11 

ft.    in. 

19     4 

ft.    in. 
21     9 

ft.  in. 
24  2 

ft.  in. 
29  0 

The  presence  of  hard  water  in  an  economizer  prevents 
the  use  of  pipes  other  than  straight  in  length  or  circular  in 
section.  No  other  pipes  are  rationally  practicable.  The 
rate  of  flow  of  water  through  the  pipes  only  averages  in 
usual  conditions  J  inch  per  minute.  When  driven  by 
electric  motor,  this  should  be  enclosed.  It  is  best  to  drive 
through  a  steel  worm  and  phosphor  bronze  wheel  in  an 
oil  bath.  The  speed  of  the  shaft  supplied  with  the  econo- 
mizer is  intended  to  be  55  per  minute. 

233 


WATER    SOFTENING   AND    TREATMENT 

The  Pure  Water   Economizer. 

In    order   to   surmount  the  scale  difficulty,  it  has  been 
proposed    to   supply   pure    soft    water  to  a   closed   cycle 


| 


y////////////////^^^^ 

*s  oN 


fc  5 


economizer,  the  water  being  kept  in  movement  by  a  pump 
and  passed  through  a  counter-current    cooler,  which  is  a 

234 


FEED    HEATING 


feed 
the 


T 


heater  to  the  real  feed.  Thus  water-heated,  the  feed 
water  will  deposit  its  lime  salts  in  a  soft  condition,  and 
the  economizer  will  always  be  free  from  scale  and  at  full 
efficiency. 

Fully  Heated  Feed  Water. 

Within  recent  years  the  advantages  of  fully  heated 
have  been  better  recognized,  and  in  connexion  with 
Cruse  system 
of  superheat 
control  a  sys- 
tem of  feed 
heating  to 
boiler  tem- 
perature has 
been  evolved. 
In  the 
Cruse  flue- 
fired  super- 
heaters, for 
example,  the 
feed  water  to- 
gether with 
water  from 
the  boiler  it- 
self is  circu- 
lated through 
a  copper  tube, 
which  is  car- 
ried in  series 
through  the 
tubes  of  the 
superheater 
placed  behind 
a  Lancashire 
boiler. 

When  the 
superheater  is 
of  the  sepa- 


OF  THE 

UNIVERSITY 

riC 


WATER  SOFTENING  AND  TREATMENT 


rately  fired  order  (Figs.  73,  74,  75)  the  same  through  con- 
trolling pipe  of  hot  water  is  employed,  but  the  water  does 
not  come  in  this  case  from  the  boiler,  but  from  the  drums 
of  a  feed  heater  which  is  placed  between  the  furnace  and 
the  superheater  tubes  to  temper  the  excessive  heat  of  the 


FIG.  75.     CROSS  SECTION  AND  END  VIEW. 


furnace  gases  to  a  safe  temperature  for  the  superheater 
tubes.  The  fresh  feed  in  this  case  is  also  mixed  with  the 
circulating  water.  In  this  way  the  water  already  hot  is 
heated  fully  to  boiler  temperature,  and  it  is  found  that 
very  much  larger  boiler  output  can  be  secured.  The  pro- 
pelling agent  which  keeps  the  water  in  movement  through 

236 


FEED    HEATING 

the  tubes  is  superheated  steam,  which  when  it  comes  into 
contact  with  the  water  becomes  at  once  saturated  only,  and, 
shrinking  in  bulk,  gives  a  work  effect  as  a  result  of  the 
condensation  of  volume. 


Stage   Heating. 

Correctly  and  best  to  utilize  practical  conditions, 
the  generation  of  steam  must,  like  its  use,  be  conducted 
in  stages.  Thus  feed  water  is  first  heated  by  the  exhaust 
steam  from  an  engine  either  at  atmospheric  pressure  or 
in  a  condenser  at  a  lower  temperature.  Next  it  acquires 
further  heat  from  the  waste  gases,  and  finally  in  the  case 
of  the  Cruse  superheater  it  is  heated  fully  up  to  the 
temperature  of  the  boiler  in  the  process  of  regulating  the 
superheat  of  the  steam. 

Even  where  this  stage  is  not  present  it  is  well  to  heat 
the  feed  by  steam  from  the  boiler,  so  that  the  full  tempera- 
ture of  the  boiler  "may  be  attained  by  the  water  before  this 
is  passed  into  the  boiler. 

The  advantage  of  this  was  first  claimed  by  M.  Normand, 
a  French  engineer.  He  claims  an  economy  of  10  to  15  per 
cent,  as  the  result  of  using  steam  from  a  boiler  to  heat  the 
water  going  into  that  boiler. 

It  is  not  as  a  rule  worth  while,  when  making  steam 
engineering  calculations,  to  take  into  consideration  the  varia- 
tion of  specific  heat.  One  pound  of  water  raised  through  1°  F. 
represents  very  closely  1  thermal  unit=  1  B.Th.U.,  and 
1  kilogramme  heated  1°  C.  is  closely  equal  to  1  calorie  = 
1  cal.  But  for  those  who  wish  a  closer  figure  the  table  XXII. 
of  Regnault's  values  of  the  specific  heat  of  water  will  be 
useful.  Rowland  considers  water  to  have  a  specific  heat  =  1 
at  15°  C.  below  which  temperature  it  rises  and  attains  to 
1-0056  at  5°C.,and  falls  to  a  minimum  of  0'9956  at  29°  C., 
when  it  rises  slowly  again  above  that  temperature.  Bartoli, 
and  also  Ludin,  assume  unity  at  15°C.,and  show  a  rise  at 
lower  temperatures,  a  minimum  of  0-9993  and  0'9988  at 
22°  C.  and  29°  C.  respectively.  Mr.  James  Weir  has  heated 
feed  water  in  the  apparatus  (Fig.  76)  by  means  of  steam 

23? 


WATER    SOFTENING    AND    TREATMENT 


taken  from  the  intermediate  receiver  of  a  compound  engine 
after  the  steam  has  done  some  work  in  the  h.p.  cylinder. 
Mr.  Weir  aimed  not  merely  at  economy,  but  also  at  the 
thorough  elimination  of  gases  from  the  water.  These  gases 
are  what  produce  corrosion  in  boilers.  In  the  Weir  heater 
they  are  drawn  off  at  the  top  of  the  apparatus.  Gases 
freshly  occluded  from  water  appear  to  have  a  peculiar  effect 
in  corrosion,  owing  probably  to  an  active  condition  due  to 
their  nascent  condition  in  the  atomic  form  before  molecular 

cohesion  has  taken 
place.  Only  by  gas 
elimination  can  thin 
tube  boilers  be  main- 
tained sound  at  sea. 

In  Fig.  76  the  Weir 
heater  is  shown  to  have 
a  float  which  regulates 
the  supply  pump  by 
means  of  a  throttle 
valve,  thus  supplying 
water  as  the  boiler  feed 
pump  draws  off  the  store. 
The  cold  water  enters 
as  a  spray,  and  meets 
the  steam  entering 
round  the  perforated 
casing.  Auxiliary  en- 
gines at  sea  may  supply 
the  steam,  and  the 
temperature  of  feed 

may  be  212°  F.  in  a  closed  heater.  Thus,  in  an  example 
cited  where  steam  was  taken  from  the  receiver  at  a  gauge 
pressure  of  16*7  lb.,  the  temperature  being  218°  F.,  water 
taken  at  100°  F.  from  the  hot  well  was  raised  to  218°  F. 
Since  steam  at  the  receiver  pressure  contains  1,080  B.Th.U., 
measured  from  100°  F.,  and  the  water  acquires  118°  of 
temperature,  this  represents  nearly  11  per  cent,  of  the  total 
available  heat  of  the  steam.  Thus  the  first  cylinder  of  an 
engine  is  improved  in  efficiency,  or  the  first  two  cylinders 

238 


Suctim  to  Hot  Pamr 

FIG.  76.     WELR  FEED  HEATER. 


FEED    HEATING 

if  there  is  a  third,  for  they  have  taken  work  out  of  the 
steam.  Where  there  is  no  waste  gas  heater,  there  can  be 
no  question  as  to  the  economy  of  the  Weir  system,  apart 
from  its  benefit  in  respect  of  corrosion. 

If  auxiliary  plant  were  always  near  to  the  main  engines, 
and  only  required  to  run  when  these  run,  it  is  probable 
that  greater  economy  would  be  secured  by  using  in  them 
throttled  receiver  steam  and  coupling  them  up  to  the  main 
condenser.  But  they  are  often  too  far  away  for  this,  and 
must  use  boiler  steam,  in  which  case  their  exhausts  can 
often  be  used  in  tubular  feed  heaters.  Very  much  in  the 
way  of  feed  heating  cannot  be  done  by  exhaust  steam  on 
its  way  to  the  condenser,  simply  because  it  so  rapidly 
acquires  condenser  temperature.  Only  about  100°  to 
120°  F.  can  be  secured,  whereas,  as  already  seen,  upwards  of 
218°  F.  has  been  acquired  by  feed  water  heated  from  the 
receiver.  In  most  cases  the  engineer  will  find  he  has  more 
heat  than  he  can  utilize.  There  are  both  waste  steam  and 
waste  gas,  and  it  is  of  no  use  employing  boiler  steam  to 
heat  the  feed  water  until  after  the  economizer,  if  present, 
has  done  all  that  is  possible. 

Surface  or  Tubular  Feed  Heaters. 

These,  of  course,  find  their  principal  employment  where 
non-condensing  engines  are  at  work.  They  all  consist  of 
tubes  variously  arranged  and  exposed  on  the  inner  surfaces 
to  exhaust  steam  or  vice  versa,  or,  when  necessary,  to  boiler 
steam  more  or  less  throttled  if  so  required. 

In  the  Row  heater  (Fig.  77)  the  tubes  are  indented  as 
though  rolled  two  ways  through  a  cogged  roller.  The 
obstructed  irregular  passage  through  the  tubes  compels 
turbulent  movement  of  the  water,  and  it  is  claimed  that 
in  a  test  with  steam  at  62  Ib.  pressure,  a  Row  tube  raised 
11  gallons  of  water  to  212°  F.  in  5J  minutes,  whereas  a 
similar  but  plain  tube  required  twice  that  time.  Similarly 
2 1  gallons  were  evaporated  in  llf  and  24  minutes  respect- 
ively. Apparently  the  indented  surface  is  doubly  as 
efficient  as  plain  surface. 

239 


WATER    SOFTENING    AND    TREATMENT 

This  form  of  tube  is  also  advocated  for  condenser  pur- 
poses and  for  cooling  surface  likewise. 


FIG.  77.     Row  FEED  HEATEB. 


The  Berryman  Heater. 

This  heater  (Fig.  78)  is  a  long-established  form  of  heater 
with  inverted  f\  tubes  of  various  lengths  suitably  expanded 

240 


FEED    HEATING 


into  a  double  chamber  base. 
Steam  passes  through  the 
tubes  and  water  rises  from  be- 
low and  is  taken  off  below  the 
scum  and  air  trap,  which  should 
have  an  escape  or  blow-off  tap. 
The  tubes  are  free  to  expand 
without  stress,  and  the  crown 
can  be  taken  off  and  the  tubes 
cleared  of  scale.  The  heating 
power  of  exhaust  steam  is  very 
great.  One  pound  contains  967 
B.Th.U.  above  212°  F.,  so  that 
it  will  heat  to  212°  F.  6  Ib.  of 
water  supplied  at  51°  F.  Obvi- 
ously, therefore,  a  non-condens- 
ing engine  will  heat  the  feed  of 
many  times  its  own  power  of 
engines  to  212°  under  ordinary 
conditions,  and  a  wasteful  direct 
steam  pump  will  heat  feed  water 
for  quite  large  main  engines  from 
the  usual  hot  well  temperature 
to  a  good  high-feed  tempera- 
ture. 


FIG.  78.     BEBBYMAN  HEATEB. 


TABLE  XXII. 
SPECIFIC  HEAT  OF  WATER  (REGNAULT). 


Temp. 

Sp.  Heat. 

Temp. 

Sp.  Heat. 

0°C  =  32°F 

1.0000 

110°C  =  230°F 

•0153 

10°=   50° 

1-0005 

120°  =  248° 

•0177 

20°=   68° 

1-0012 

130°  =  266° 

•0204 

30°=   86° 

1»0020 

140°  =  284° 

•0232 

40°  =104° 

1-0030 

150°  =  302° 

•0262 

50°  =122° 

1-0042 

160°  =  320° 

•0294 

60°  =140° 

1-0056 

170°  =  338° 

•0328 

70°  =158° 

1-0072 

180°  =  356° 

•0364 

80°  =  176° 

1-0098 

190°  =  374° 

•0401 

90°  =194° 

1-0109 

200°  =  392° 

•0440 

100°  =  212° 

1«0130 

241 


WATER  SOFTENING  AND  TREATMENT 

The  specific  heat  of  water  is  taken  as  1*00  at  0°  C.  =  32°  F. 
The  table  XXII.  gives  Regnault's  figures,  which  are  probably 
not  far  wrong.  Some  observers,  however,  give  figures  less 
than  unity  above  0°  C.  In  either  case  the  variation  in  the 
specific  heat  is  of  no  consequence  to  the  engineer. 

Similarly  water  does  not  vary  very  much  in  bulk  with 
variation  of  temperature,  as  shown  by  the  following  table 
(XXIII.)  of  weight  per  cubic  foot  in  Ib. 


TABLE  XXIII. 

EXPANSION  OF  WATER. 


Temp. 

Weight. 

Temp. 

Weight. 

Temp. 

Weight. 

212°F 
250° 
300° 

102° 

59-71 
58-81 
57-26 

62-00 

350°F 
400° 
450 

158° 

55-52 
53-64 
50-66 

61-00 

500°F 
500° 

62° 
203° 

49-61 
47-52 

62-2786 
60-00 

Up  to  boiling  point  in  the  open  air,  therefore,  the  ex- 
pansion is  under  5  per  cent,  of  the  bulk  at  62°  F. 

The  maximum  density  of  water  is  at  4°  C.  =  39' 1°  F. 
To  melt  1  Ib.  of  ice  at  32°  F.  to  water  at  32°  F.  requires 
142B.Th.U.=  35*78  calories  per  pound  or  78*86  calories 
per  kilogramme.  To  evaporate  1  Ib.  of  water  at  212°.  F. 
into  steam  at  212°  F.  requires  965-7  B.Th.U. 

The  imperial  gallon  of  pure  distilled  water  at  62°  F. 
weighs  10  Ib.  by  law,  and  measures  277*479  cubic  inches. 
The  American  gallon  is  the  old  wine  gallon  of  8J  Ib.,  and 
measures  231  cubic  inches.  It  is  important  to  remember 
this,  for  on  one  occasion  known  to  the  Author  a  smart 
American  salesman  sold  locomotives  to  a  colonial  Govern- 
ment on  the  strength  of  the  greater  capacity  of  their  tetider 
tanks,  whereas  the  rival  English  engines  were  of  consider- 
ably greater  capacity. 

Tray  Feed  Heaters. 

Under  the  head  of  "  Water  Softening,"  reference  has 
already  been  made  to  the  Chevalet-Boby  heater  detartarizer, 

242 


FEED    HEATING 

Similar  effects  in  softening  are  obtained  by  allowing  the 
feed  water  to  enter  a  boiler  by  way  of  a  number  of  shallow 
overflow  trays.  By  this  means  feed  heating  and  scale 
deposit  are  effected  in  the-  trays,  and  this  is  better  than 
direct  flow  of  cold  water  into  a  boiler.  The  trays  catch 
the  lime  salts  as  they  are  caused  to  separate  by  heat  and 
adhere  to  them.  The  trays  should  be  in  duplicate  and 
easily  removable.  As  soon  as  removed,  and  while  still  wet 
and  soft,  the  scale  can  be  easily  knocked  off.  To  throw 
down  sulphate  of  lime  a  little  carbonate  of  soda  is  used  in 
the  feed. 

The  Cochrane  heater  is  also  a  combination  heater  and 
purifier,  steam  from  an  engine  entering  through  an  oil 
separator  and  passing  upwards  between  the  trays,  over 
which  the  water  is  trickled.  The  heated  water  passes 
through  a  coke  filter  below,  and  this  arrests  the  last  of  the 
deposit.  It  is  claimed  for  all  these  various  purifier  heaters 
that  the  oil  not  removed  by  the  mechanical  separator  is 
absorbed  by  the  scale  deposit  which  adheres  to  the  trays. 

Needless  to  say,  these  contact  heaters  are  far  more 
efficient  per  unit  of  space  occupied  than  are  surface  heaters. 


243. 


CHAPTER  XXV 

THE  PRACTICAL  APPLICATION  OF 
STAGE  HEATING  IN  THE  GENERATION  OF  STEAM 

IN  order  more  fully  to  illustrate  what  the  Author  considers 
to  be  the  correct  principles  of  steam  engineering  and 
the  particular  relation  of  the  feed-heating  stages  to  the 
general  scheme  of  the  heating  of  the  working  fluid  of  the 
steam  engine,  he  has  selected  the  accompanying  illustrations 
of  the  "  Cruse  "  or  "  Quad  "  boiler  because  they  show  as 
much  as  it  is  possible  in  one  combined  apparatus  each  stage 
into  which  practical  considerations  make  it  economically 
necessary  to  divide  the  whole  operation  of  steam  making. 

The  illustrations  represent  a  "  Cruse  "  straight- tube  three 
drums  boiler,  combined  with  a  double-tube  economizer,  a 
feed  reheater  and  purifier,  and  a  controllable  superheater. 

The  feed  water,  already  heated  to  90°  F.  or  100°  F.,  whether 
because  it  comes  from  a  surface  condenser,  or  has  been 
heated  by  an  injector,  is  passed  into  the  inter-circulating 
double- tube  economizer,  which  is  placed  in  the  path  of 
the  waste  gases  from  the  boiler.  The  practical  necessity  of 
feeding  an  economizer  with  warmed  water  has  been  explained 
when  dealing  with  economizers.  In  this  economizer  the 
water  acquires  what  heat  it  can  obtain  from  the  nominally 
waste  gases  ;  it  is  fed  into  the  bottom  and  rises  from  the 
top  box  to  the  upper  side  of  the  feed-reheating  4rums, 
which  it  enters  through  the  inlet  valve  and  falls  in  jets  or 
in  broken  sheets  from  a  perforated  pipe  upon  the  series  of 
perforated  plates  forming  a  shed,  the  perforations  being  in 
the  vertical  parts  of  the  plates.  Inside  the  space  enclosed 
by  these  plates,  steam  is  admitted  from  the  boiler  to  act 
upon  the  broken  sheets,  or  the  spray  of  falling  water,  and 

244 


PRACTICAL  APPLICATION  OF  STAGE  HEATING 

the  feed  water  is  thus  raised  to  the  full  temperature  of  the 
boiler.  The  steam  space  in  this  feed-heater  drum  is  in  free 
communication  with  the  steam  space  of  the  drums  of  the 
boiler,  and  is,  therefore,  continuously  supplied  with  all  the 
steam  necessary  to  make  up  that  which  disappears  by  the 
condensation  resulting  from  contact  with  the  feed  water  ; 
the  water  space  of  this  drum  is  likewise  in  open  communica- 
tion with  the  water  space  of  the  drums  of  the  boiler,  and 
thus  the  boiler  proper,  being  fed  with  water  at  the  full 
temperature  of  the  working  pressure,  is  free  to  perform 
only  its  proper  duty  of  evaporation. 

The  saturated  steam  generated  in  the  boiler  passes  from 
the  steam  and  water  drums  into  the  two  saturated  steam 
domes,  whence  it  is  led  to  the  15-inch  collector,  from  which 
it  is  distributed  to  the  various  sections  of  the  superheater. 
This  superheater  should  theoretically  be  next  to  the  furnace, 
but  the  limited  endurance  of  steel  compels  here  a  departure 
from  mere  theory,  and  the  superheater  tubes  are  therefore 
placed  behind  the  first  bank  of  the  heating  tubes  in  a  zone 
of  temperature  which  they  can  endure.  This  superheater 
internally  is  fitted  with  water-control  tubes,  through  which 
a  stream  of  water  is  propelled  by  a  superheated  steam 
inspirator.  The  water  is  drawn  from  the  front  drum  of 
the  boiler  and  delivered  through  the  control  tubes  to  the 
back  drum,  acquiring  heat  on  its  way  from  the  heating 
gases  and  through  the  steam  which  is  being  superheated. 
This  control  system  not  only  governs  the  temperature  of 
superheat  within  a  narrow  range,  but  serves  to  protect  the 
superheater  tubes  also,  and  this  more  especially  when  steam 
ceases  to  be  drawn  through  the  superheater  for  power,  for 
then  the  flowing  water  continues  to  absorb  and  carry  off 
heat,  abstracting  it  from  and  through  the  superheating  tube 
shells,  while  it  also  compels  some  steam  to  flow  through  the 
superheater  tubes  and  uses  this  flow  to  maintain  its  own 
active  circulation,  the  two  effects  combining  to  avert  over- 
heating of  the  superheater  tube  metals. 

By  the  combination  of  the  four  distinct  sections  or 
elements  which  go  to  make  up  this  "  Quadriunial  "  boiler, 
the  stage  production  of  steam  is  carried  out  as  nearly  upon 

245 


WATER    SOFTENING   AND    TREATMENT 

correctly  scientific  lines  as  practical  considerations  enable 
it  to  be  done  ;  that  is  to  say,  the  furnace  heat  at  maximum 
temperature  is  applied  to  the  working  fluid  at  maximum 
temperature,  and  this  maximum  temperature  is  first  acquired 
by  the  water  as  far  as  possible  from  heat  that  would  other- 
wise be  wasted. 

Large  downcomer  pipes,  external  to  the  boiler  casing, 
ensure  perfect  and  regular  circulation,  and  large  equalizer 
pipes,  also  external  to  the  boiler  casing,  maintain  the  water 
level  of  the  two  drums  equal  throughout. 

Any  section  of  the  superheater  can  be  cut  out  and  its 
four  'connexions  blank  flanged  ;  if  necessary,  the  whole 
superheater  can  be  lifted  out  between  the  top  saturated 
steam  domes  and,  the  four  main  connexions  having  been 
blank  flanged,  the  boiler  can  be  worked  without  the  super- 
heater. 

The  boiler  as  illustrated  is  the  first  complete  and  self- 
contained  combination  of  apparatus  for  the  production  and 
superheating  of  steam  on  the  lines  of  stage  heating  recog- 
nized as  correct,  each  stage  taking  place  in  a  separate 
vessel.  This  boiler  therefore  represents  the  most  perfect 
practice  in  steam  generation  hitherto  evolved.  The  only 
departures  from  strict  theory  are  in  such  points  as  the 
limitation  of  the  capacity  of  endurance  of  materials  renders 
necessary.  • 

A  notable  feature  in  the  boiler  proper  is  that  all  the 
downward  circulation  of  the  water  takes  place  in  large 
downcomer  pipes  outside  the  external  casing  and  the  up- 
ward circulation  takes  place  entirely  by  the  small  heated 
tubes  which  are  all  at  right  angles  to  the  furnace  and  face 
the  direction  of  flow  of  the  gases  from  the  furnace. 

The  following  is  abstracted  from  Mr.  Cruse's  own  aicount 
of  the  combination  patented  by  him  and  embracing  the  four 
main  stages  of  steam  generation  in  one  seating  or  enclosed 
space. 

The  "  Quad  "  superheated  steam  generator  combines  in 
one  compact  enclosure  the  four  integrants  of  the  process  of 
steam  generation. 

246 


PRACTICAL  APPLICATION  OF  STAGE  HEATING 


FIG.  79.     CROSS  SECTION  (Enlarged  Scale). 
247 


WATER  SOFTENING  AND  TREATMENT 

1.  An    inter-circulating     tubular     feed-water    heater    or 
"  Economizer." 

2.  A  cylindrical  steam-heated    feed-water  re-heater  and 
purifier  or  "  Hyper  therm." 

3.  A  vertical  straight  tube  boiler  or  "  Evaporator." 

4.  A  water-tube-controlled  steam  superheater. 

These  units  form  the  four  progressive  stages  into  which 
practical  steam  raising  is  divided,  and  each  unit  works 
independently  of,  although  correlatively  with,  the  others. 

The  "  Economizer  "  is  constructed  of  seamless  steel  tubes, 
each  containing  a  smaller  internal  tube,  open  top  and 
bottom ;  this  allows  of  a  rapid  and  constant  internal 
circulation  in  each  tube,  combined  with  the  general  forward 
movement  of  the  mass.  The  tube  plates  and  dishes  forming 
the  top  and  bottom  boxes  are  of  wrought  steel.  The  inter- 
circulating  action  adds  to  the  efficiency  of  this  class  of 
apparatus  and  minimizes  corrosion.  The  feed  from  the 
condensers  is  fed  into  the  bottom  boxes,  and  leaves  the 
top  boxes  much  raised  in  temperature  and  travels  to  the 
re-heater  drum  above. 

The  re-heater  or  "  Hypertherm  "  is  a  rivetted  steel  drum, 
provided  with  a  cast-iron  perforated  water- distributor  pipe 
and  shed  in  the  steam  space,  and  with  a  perforated  water- 
collector  pipe  in  the  water  space.  It  has  a  large  mud 
pocket  and  blow-off  pipe,  and  steel  steam-inlet  blocks  and 
pipes  and  steel  water-outlet  blocks  and  pipes,  connecting 
it  respectively  to  the  steam  and  water  spaces  of  the  boiler 
drums.  The  feed  water  from  the  economizer  enters  through 
the  valve  at  top  at  economizer  temperature,  and  leaves  for 
the  boiler  drum  by  the  pipes  at  bottom  at  boiler-pressure 
temperature. 

The  boiler  proper  or  "  Evaporator  "  is  composed  of  t$vo 
top,  or  steam  and  water,  drums  and  one  large,  or  two  small, 
bottom  water  drums.  The  drums  are  interconnected  by 
small  seamless  steel  heating  tubes  and  by  large  seamless 
steel  downcomer  and  equalizer  pipes.  The  large  down- 
comer  and  water-level  equalizer  pipes  are  all  outside  the 
boiler  casing,  and  are  connected  to  the  drums  by  rivetted 
blocks.  The  small  heating  tubes  are  straight  and  are  simply 

248 


PRACTICAL  APPLICATION  OF  STAGE  HEATING 

expanded,  or  they  may  be  staved  at  each  end  and  screwed 
and  expanded  into  specially  rolled  and  shaped  concave 
steel-tube  plates  rivetted  to  the  drum  shells  in  the  form  of 
butt  straps.  The  tubes  are  not  directly  expanded  into  the 


FIG.  80.     SECTION  THROUGH  FURNACE. 
249 


WATER    SOFTENING   AND    TREATMENT 

drum  shell,  but  the  corresponding  holes  in  the  drum  shell 
are  bored  to  a  larger  diameter  to  allow  the  tube  ends  to  be 
bell-mouthed  over  the  counter-sunk  shoulder  formed  on  the 
butt  strap.  These  tube  plates  are  exceptionally  strong,  and 
in  addition  to  permitting  the  use  of  straight  tubes  entering 
non-radial  to  the  drum,  without  the  necessity  of  departing 
from  the  cylindrical  form  of  the  shell,  they  strengthen  the 
shell  plate  at  its  weakest  section,  i.e.  where  it  is  drilled  for 
the  admission  of  the  tube  ends. 

The  top  drums  are,  for  water-tube  boilers,  exceptionally 
large ;  the  containing  capacity  of  the  combined  steam 
spaces  equals,  approximately,  600  cubic  feet  ;  while  the 
water  spaces,  from  working  level  to  above  the  line  of  the 
tube  ends,  give  a  water-storage  capacity  equal  to  one  and 
a  half  hour's  evaporative  duty — 30,000  Ib. 

The  top  drums  are  surmounted  by  two  longitudinal 
ri vetted  steam  drums  or  domes,  with  safety  valves  and 
outlet  branches  to  the  superheater  collector  ;  the  steam  is 
drawn  at  mid  height  of  the  domes,  and  thus  an  ample 
steam-separating  or  anti-priming  chamber  is  formed,  the 
entrained  water  being  allowed  to  fall  and  return  to  the 
main  drums. 

The  superheater  is  a  form  of  the  Cruse  controllable  type, 
and  is  made  up  of  a  number  of  elements  assembled  fore  and 
aft  by  means  of  the  saturated  or  inlet  steam  collector  and 
the  superheated  or  outlet  steam  collector  pipes.  The  con- 
trol water  system  is  connected  to  the  front  drum  by  the 
front- water  collector  and,  through  each  element,  by  the 
back-water  collector  to  the  back  drum.  The  control,  or 
government  of  the  temperature  of  superheat,  is  maintained 
and  adjusted  by  means  of  the  superheated  steam  inspirators 
at  each  end  of  the  front-water  collector.  This  waterrtube 
controlling  system  may  also  be  connected  to  the  feed-heater 
drum,  to  the  economizer,  or  direct  to  the  condenser.  The 
front  or  superheated  steam  collector  carries  a  safety  valve 
and  necessary  outlet  blocks. 

This  boiler  is  provided  with  all  necessary  safety  and  stop 
valves,  water-level  valves  and  steam  and  water-level  indi- 
cators, pressure  gauges,  blow-off  pipes  and  cocks,  drain 

250 


PRACTICAL  APPLICATION  OF  STAGE  HEATING 

pipes,  etc.  ;   with  stanchions  and  girders  and  with  ordinary 
furnace  bars,  or  with  special  mechanical  stokers. 


FIG.  81.     PLAN  (Enlarged  Scale). 
251 


WATER  SOFTENING  AND  TREATMENT 

The  boiler  illustrated  has  an  evaporative  capacity  of 
20,000  Ib.  of  water  per  hour,  rated  from  and  at  212°  F.  ; 
from  feed  water  at  100°  F.  into  steam  at  160  Ib.  working 
pressure,  superheated  200°  F.,the  fuel  being  North- Country 
coal  of  a  calorific  value  equal  to  14,000  B.Th.U.  per  pound, 
the  guaranteed  coal  efficiency  being  75  per  cent. 

Ground  space  covered  by  this  generator  :— 

Length  :  from  .outside  furnace  mouth  to  damper  at  back 
-22  ft. 

Width  :   over  drums — 19  ft. 

Gangway — 3  ft. 

Height :   28  ft.  from  firing  floor. 

From  the  foregoing  details  and  the  illustrations  it  will  be 
found  that  the  process  of  steam  manufacture  on  scientific 
lines  can  be  carried  out  with  an  apparatus  constructed 
within  a  small  space,  yet  readily  accessible.  Steam  raising 
is  seen  to  be  an  operation  involving  a  good  deal  of  judgment 
in  regard  to  the  means  to  be  employed,  and  no  inconsidered 
compromise  between  narrow  theoretical  views  and  practical 
conditions.  Thus  the  dictum  of  theory  is  that  all  heat 
ought  to  be  applied  at  the  top  temperature  ;  but,  in  the 
first  place,  it  is  not  practicable  to  employ  a  working  fluid 
so  hot  as  the  source  of  heat ;  and,  secondly,  it  is  not 
practical  to  throw  away  low-temperature  heat.  Hence  the 
system  of  stage  heating,  as  here  illustrated,  as  a  scientific 
compromise  of  many  conflicting  elements. 


252 


Section   IV 
WATER  COOLERS 


253 


CHAPTER  XXVI 
WATER  COOLING 

UNLESS  a  river,  or  a  canal,  or  a  large  pond  is  available 
for  condensing  purposes  artificial  means  must  be 
employed  to  reduce  the  temperature  of  condensing  water  to 
a  point  sufficiently  low  for  efficient  use  in  condensing 
apparatus. 

The  ordinary  methods  of  cooling  are  four  in  number, 
viz  : — 

(a)  The  pond  ;  (b)  the  atmospheric  evaporative  surface  ; 
(c)  the  tower  ;  (d)  the  spray  apparatus. 

Whatever  system  of  cooling  is  employed  all  depend  on 
the  principle  of  rendering  heat  latent  by  assisting  the  evapor- 
ation of  part  of  the  water  to  be  cooled  by  means  of  the 
absorptive  power  of  air.  Each  pound  of  water  which  is 
carried  off  as  vapour  by  a  current  of  air  bears  with  it  966 
units  of  heat  in  latent  form  apart  from  any  sensible  heat 
acquired  by  the  air  as  a  result  of  its  contact  with  the  warm 
water. 

In  the  annexed  table  (XXIV.)  are  given  some  figures 
relative  to  the  moisture  carrying  properties  of  air. 

The  actual  amount  of  water  that  it  is  possible  to  absorb 
varies  with  the  amount  of  dryness  of  the  air,  and  in  misty 
weather,  when  most  required  in  many  cases,  a  cooler  loses 
much  of  its  efficiency  from  this  fact. 

If  it  be  assumed,  as  above,  that  air  will  carry  off  5  per 
cent,  of  its  weight  of  moisture,  then  100  Ib.  or  1,300  cubic 
feet  of  air  should  carry  off  about  5,000  heat  units.  Fans 
must  be  provided  to  supply  300  cubic  feet  of  air  or^  23  Ib. 
for  each  pound  of  steam,  whence  the  Author's  rough  rule 

255 


WATER    SOFTENING   AND    TREATMENT 


TABLE  XXIV. 

HYGROMETRIC  PROPERTY  OF  AIR. 

0            T£        iO 

0       Op       4 

1     O    co 

20,000  cubic  feet  of  saturated  air  at  90°  contains  47  Ib.  of  water. 
At  60°  the  same  volume  contains  17  Ib.  only. 

emperatures 

o     ^ 

o  . 

TfH    IO 
l-H    l-H 

b   ?   *° 

Ol      i—  I      CO 

o     00 

w5? 

l-H   i-H 

O          l>»           i. 

g  2  s 

•fa 

CQ 
P 

O 

1 

1 
§ 

i 

CQ 
gj 

'3 

t 

"8 

pd 

8 

J. 
^ 

o 

Ti 
<X> 

1 
j 

i 

1 

r 

"8 

i 

6 

*i 

12 

02 

eg 

2,-,   "^ 

S^1? 

i—  1  GO 

o    %   S 

•*    A   °° 

2«  »o 

CO   ^H 

rH    0 

§  1  i 

1! 

i  S  § 

°o? 

O5  eo 

o    9    °° 
£    ob    « 

^§ 
00  C?J 

00 

o    9    *~ 

GO      0     <* 

o     JS 
t^  OS 

l>  ^ 

1C 
0          GO       CO 

i  ^  N 

I—  1 

0       ^ 

00  ^ 
«  4n 

0           ^ 

0      00      10 
O      oj      <N 

fe§ 

10  ^ 

Temperature  
Water  in  1  cubic  foot  of  saturated  air  in") 
grains  .  .  .  ) 
Percentage  of  water  deposited  for  fall  of  10° 

0       ^ 

g? 

0rtS 

TH    » 

ll 

Temperature  .  F° 
Moisture  .  .  .  Ib. 

256 


WATER    COOLING 

that  the  weight  of  air  is  to  be  equal  to  the  weight  of  circu- 
lating water  under  ordinary  general  conditions. 

But  it  must  not  be  assumed  that  the  air  commences  dry. 
Possibly  it  starts  with  2  per  cent,  of  moisture  and  escapes, 
say,  with  4  per  cent,  instead  of  5  per  cent.  Then,  in  place 
of  23  lb.,  or  say  24  Ib.  of  air  per  pound  of  steam,  the  weight 

5      4 
required  would  be  24  x  -  x  -  =  60  lb. 

As  a  fact  no  calculation  ought  to  be  based  on  the  amount 
of  circulation  water  unless  it  be  the  general  size  of  the  tower. 
The  essential  fact  is  the  number  of  thermal  units  in  the 
exhaust  steam,  which  may  be  assumed  as  1,000  units  per 
pound  and  in  the  long  run  it  is  this  heat  that  has  to  be  carried 
off  by  the  air.  If  always  thermal  units  alone  are  considered, 
it  will  greatly  simplify  calculations  and  place  each  calculated 
item  of  air,  cooling  water,  etc.,  by  itself,  independent  of  the 
other  variables.  Practically  one  might  say  that  the  air 
passed  through  a  cooling  tower  must  carry  off  half  the  heat 
of  the  coal  burned  in  the  furnaces. 

After  a  calculation  has  been  made  on  the  estimated  capa- 
city of  the  plant  with  a  given  weight  of  air,  something  like  10 
per  cent,  should  be  allowed  as  a  margin  for  imperfect  satura- 
tion of  the  air  and  there  should  be  a  margin  of  fan  speed 
available  in  case  of  poor  conditions.  Thus,  in  round  numbers, 
25  lb.  of  air  may  be  provided  per  pound  of  feed  water  and 
the  power  to  lift  this  air  to  the  top  of  the  cooler  will  be 
double  that  necessary  to  lift  the  water,  except  that  actually 
the  air  is  expanded  and  lifted  by  the  heat  of  the  descending 
water  and  the  fan  power  provides  what  is  necessary  to  add 
to  the  natural  velocity  and  to  overcome  the  downward 
tendency  induced  in  the  air  by  the  down-flowing  water. 

For  practical  purposes,  13  cubic  feet  of  air  may  be  taken 
as  weighing  1  lb.  at  the  ordinary  mean  temperature  in  this 
country. 

Only  by  a  counter-current  system  can  the  full  effect  of  the 
hygroscopic  quality  of  air  be  utilized,  but  under  cooling- 
tower  conditions  it  should  be  possible  to  discharge  the  cool- 
ing air  fully  saturated  at  the  temperature  of  the  entering 
water. 

257  s 


WATER    SOFTENING   AND    TREATMENT 

The  Pond. 

The  essentials  of  a  pond  are  such  a  capacity  and  such  an 
area  as  will  suffice  to  cool  the  water  to  a  sufficiently  low 
temperature  before  the  whole  mass  of  water  has  made  a 
complete  circuit  of  the  pond  and  condenser.  Preferably, 
the  pond  must  be  below  the  condenser  so  as  not  to  call  for 
too  heavy  a  lift  on  the  air  pump  if  this  is  part  of  a  jet  con- 
denser. With  a  surface  condenser  the  circulating  pump 
should  be  part  of  a  closed  circuit  with  the  condenser,  the 
indraught  and  discharge  pipes  both  extending  below  the 
water  surface,  so  that  the  work  of  the  pump  is  merely  fric- 
tional.  A  good  jet  condenser  will  lift  its  own  injection  water 
17  or  20  feet  from  the  pond  by  the  "  vacuum  "  only. 

Mr.  Barker1  found  that  with  the  most  unfavourable 
conditions  of  atmosphere  and  location  the  cooling  of  water 
in  a  pond  may  be  as  low  as  190B.Th.U.  per  square  foot  per 
hour,  even  with  high-surface  temperature  of  the  water,  but 
with  better  exposure  and  the  same  atmospheric  conditions 
as  many  as  290  B.Th.U.  will  be  dissipated.  Under  favour- 
able conditions  the  dissipation  of  heat  will  reach  600  B.Th.U. 
per  square  foot  per  hour.  • 

Hence  it  is  concluded  that  a  reservoir  should  have  18 
square  feet  of  surface  per  10,000  thermal  units  per  hour. 
Thus,  an  engine  of  1,000  h.p.,  using  12  Ib.  of  steam  per  hour 
per  h.p.,  will  reject  about  1,000  x  12  x  1,100  heat  units 
per  hour  =  13,200,000  units,  requiring  an  area  of  23,760 
square  feet  of  cooling-pond  surface,  equivalent  to  a  pond 
about  50  yards  square.  Obviously,  the  area  of  a  pond  must 
be  thus  calculated  from  the  weight  of  feed  water  and  not 
from  the  engine  horse-power,  since  so  much  depends  on  the 
economy  of  the  engine. 

The  above  is  a  minimum  value.  For  margin  it  woulcj  be 
well  to  allow  2  square  feet  per  1,000  B.Th.U.  to  be  dispersed. 

Nor  should  the  capacity  be  less  than  10  cubic  feet  for  the 
same  1,000  thermal  units.  This  implies  a  pond  about  5  feet 
deep,  but  there  is  no  higher  limit  of  depth  so  long  as  the 
surface  is  maintained. 

1  Mins.  of  Proc.  I.C.E.,  vol.  cxxxii.  pt.  2. 

258 


WATER    COOLING 

In  order  that  there  shall  be  no  short  circuit  of  the  hot 
water,  baffle  walls  are  built,  round  or  over  and  under  which 
the  water  must  travel  on  its  path  back  again  to  the  con- 
denser. 

The  temperature  of  the  water  has  a  great  effect  on  the 
rate  of  cooling  and  an  increase  of  mean  temperature  by 
17°  F.  has  been  observed  to  increase  the  rate  of  cooling  by 
41  per  cent. 

In  still  air  the  evaporation  being  called  unity,  was  found 
by  Dr.  Dalton  to  become  1»28  for  a  gentle  wind  and  1*57  for  a 
brisk  wind.  The  water-laden  character  of  the  air  will  affect 
cooling  and  a  dry  though  warm  air  will  readily  produce  a 
better  cooling  effect  than  a  cold  but  moist  atmosphere. 

Obviously  by  the  law  of  mixed  vapours  moisture  will 
rise  from  a  water  surface  and  permeate  the  space  above  it 
to  just  such  proportion  as  is  due  to  the  temperature  of  the 
water  surface  and  to  the  amount  by  which  the  air  above  is 
wanting  in  moisture. 

Cooling  is  a  double  effect  of  radiation  and  evaporation  or 
air  absorption.  The  air  also  abstracts  heat  by  actual  con- 
duction. Not  much  heat  is  lost  through  the  earth  bottom 
of  a  pond. 

A  puddled  reservoir,  says  Mr.  Barker,  will  cost  from  \\d. 
to  2d.  per  cubic  foot  capacity,  an  average  of  four  costing 
I'lld.  The  cost  will  be  less  where  excavated  material 
is  run  into  banks,  for  this  saves  half  the  excavation  and 
probably  three-fourths  of  the  spoil  wheeling  for  an  equal 
capacity. 

A  reservoir  of  19,143  square  feet  area  and  a  capacity  of 
127,000  cubic  feet  cost  £920. 

Concreted  reservoirs  cost  from  2*2d.  to  4»2rf.,  or  an  average 
of  3-2d.  per  cubic  foot. 

The  cheapest  pond  is,  of  course,  that  dug  entirely  in  clay 
and  banked  with  the  excavated  material.  The  bank  should 
preferably  be  pitched  with  stone  pitching  on  edge  or  brick 
on  edge,  and  the  top  and  outer  slope  grass  sown. 

The  capacity  of  the  bank  should  be  calculated  exactly  to 
absorb  the  material  excavated. 

The  inner  slope  should  be  flat — about  two  to  one.  The 

259 


WATER    SOFTENING   AND    TREATMENT 

top  of  the  bank  need  not  be  wider  than  necessary  for  a  path 
and  the  sodded  outer  slope  may  be  one  in  one  for  so  un- 
important a  pond  as  a  shallow  reservoir,  especially  where 
half  dug  out  of  the  solid. 

The  Atmospheric  Evaporator. 

Next  to  the  pond  comes  the  atmospheric  evaporator. 
Primitive  examples  of  these  have  existed  for  a  long  time  in 
the  shape  of  stacks  of  branches  over  which  the  water  to  be 
cooled  was  discharged  and  cooled  by  the  wind  before  enter- 
ing a  perhaps  too  small  pond.  Similarly  it  is  customary  to 
compel  the  hot  water  to  make  a  circuit  of  the  pond  in  shallow 
wooden  troughs  before  it  re-enters  the  pond.  The  rapid 
rippling  assists  cooling. 

The  modern  evaporative  cooler  is  built  up  of  clusters  of 
thin  pine  boards,  nailed  vertically  and  suspended  from 
cross-pieces  and  fed  on  their  upper  edges  from  a  system  of 
troughs,  which  again  took  the  drippings  from  an  upper  set 
of  vertical  boards  similarly  suspended  but  turned  90°  in 
plan  from  those  below,  so  as  to  give  an  equal  exposure  on 
the  average  to  every  wind.  Each  of  the  sets  of  boards  is 
about  9  feet  in  height,  the  total  height  of  an  apparatus  being 
about  25  feet  above  the  surface  of  the  collecting  tank  below. 
With  ample  surface  the  water  may  be  cooled  below  the 
temperature  of  the  passing  air.  An  outside  open  wall  of 
louvre  boards  is  sometimes  arranged  to  prevent  spray  being 
blown  away.  The  ground  space  for  such  an  apparatus 
capable  of  cooling  30,000  gallons  per  hour  is  1,200  square 
feet  and  a  height  of  13  feet  would  be  sufficient. 

Mr.  Koppel  allows  an  area  of  208  feet  for  2,000  gallons, 
738  feet  for  20,000  gallons  and  2,520  feet  for  100,000  gallons 
per  hour,  but  in  his  apparatus  the  drizzling  boards  ^are 
horizontal. 

Tower  Coolers. 

The  next  development  of  artificial  cooling  is  the  tower, 
built  to  act  as  an  up-cast  chimney  around  the  foregoing 
apparatus. 

260 


WATER    COOLING 


Vnponr  outlet 


The  chimney  effect  depends  on  temperature,  and  is  thus 
more  efficient  as  temperature  rises  and  needs  better  cooling. 
The  closed-in  wooden  tower  above  the  cooling  stacks  in  Fig. 
82  provides  the  chimney  effect  and  the  capacity  is  stated  to 
be  2,000  gallons  per  hour  cooled  above  a  floor  space  8  feet  x 
8  feet,  with  a  total  height 
of  46  feet.  1 

It  should  be  remembered 
in  regard  to  cooling  towers 
that  though  their  object  is 
to  cool  water,  the  immediate 
object  to  be  aimed  at  is  the 
saturation  of  air  with  mois- 
ture, so  that  the  aim  should 
be  to  split  up  the  air  in  its 
passage  and  introduce  it  to 
the  maximum  area  of  wet 
surface.  Obviously  cooling 
can  only  occur  where  suffi- 
cient weight  of  air  is  provided 
to  carry  off  heat,  and  the 
hotter  the  air  is  made  the 
more  heat  it  will  carry  off. 
Hence  the  propriety  of  the 
air  leaving  at  the  entry  of 
the  water,  so  as  to  attain  a 
maximum  temperature  and 
absorb  a  maximum  of  mois- 
ture. 

In  the  tower  of  Doherty  & 
Donat  of  Manchester,  wood- 
en-inclined horizontally  laid 

battens  are  employed,  the  Fm  82  CHIMNEY  COOLING  TOWEB. 
water  dripping  from  layer  to 

layer  of  these  through  the  up-current  of  air.  Tests  made  at 
Birkenhead  with  this  tower  showed  a  vacuum  of  26 '9  inches, 
and  cooling  from  95-6°  F.  to  66-6°  F.  The  air  which  passed 
through  attained  a  humidity  of  92-6  per  cent,  of  saturation, 
the  air  having  an  initial  temperature  of  44'7°. 

261 


outlet 


WATER    SOFTENING    AND    TREATMENT 

Generally  any  construction  of  tower  can  be  obtained, 
either  fan-cooled  or  chimney-cooled. 

In  the  chimney  cooler,  as  shown  in  Fig.  82,  the  hotter  the 
water  the  greater  will  be  the  up-draught,  and  so  far  a  sort 
of  automatic  regulation  is  provided,  but^  since  the  draught 
depends  on  difference  of  temperature,  the  cooling  effect 
cannot  be  so  great  as  in  an  open  apparatus  freely  exposed 
to  a  horizontal  breeze.  Nevertheless,  the  tower  is  more 
generally  good  for  all  conditions. 

The  dimensions  of  these  towers  for  four  capacities  are  as 
follows  : — 

2,000  gallons  per  hour.  Height,  46  ft.  Floor  Space,    8  ft.  x    8ft. 

20,000         „             „  „         57,,  „         „     19  ft.  x  19ft. 

100,000         „              „  „          65  „  „         „     58  ft.  x  24ft. 

300,000         „              „  „          80,,  „         „   164ft.  X  24ft. 

These  tower  coolers  are  large  and  heavy  affairs  and  must 
have  good  foundations  and  be  calculated  to  stand  a  wind 
pressure,  if  exposed,  of  30  Ib.  per  square  foot. 

They  throw  off  huge  volumes  of  steam  and  wet  air  and 
ought  to  be  well  away  from  buildings,  which  will  be  seriously 
damaged  by  the  discharge. 

Though  wooden  towers  are  cheaper,  those  of  iron  are 
more  durable. 

A  natural  draught  tower  standing  on  a  total  floor  space 
30  feet  square,  will  cool  the  water  necessary  to  condense 
30,000  Ib.  of  steam  per  hour  if  provided  with  earthenware- 
pipe  filling.  A  fan  tower  of  equal  capacity  would  occupy  a 
space  25  ft.  6  in.  x  24  ft.  With  a  filling  of  split-metal  tubes 
the  floor  space  for  these  two  towers  would  be  reduced  to 
26  ft.  x  26  ft.  and  18  ft.  x  16  ft.  6  in.  respectively.  As 
stated  later,  English  practice  may  require  more  liberal 
design. 

Fan  Cooling  Towers. 

To  ensure  greater  certainty  of  effect  towers  are  often 
made  lower  and  air  is  forced  through  them  by  fans.  They 
do  not  depend  on  temperature  for  their  effect,  but  of  course 
they  require  power  to  drive  the  fans.  Apart  from  the  fan 

262 


WATER    COOLING 


draught  they  can  be  filled  with  the  same  drizzling  boards  as 
some  of  the  wooden  towers.  They  are,  however,  often 
filled  with  galvanized  woven  steel  mats,  with  short  drain 
tiles  on  end  or  with  short  lengths  of  interlaced  split-steel 
pipes.  The  object  is  to  divide  and  turn  over  the  descending 
water  repeatedly  and  continually  in  its  descent  through 
the  rising  air. 

Mr.  Koppel's  figures  for  ground  space  occupied  by  a  fan 
tower  are  11  ft.  x  13ft.  for  20,000  gallons  per  hour  and 
18  ft.  x  24ft.  for  100,000 
gallons.  He  gives  the  brake 
horse-power  of  the  fan 
motors  as  2  for  a  capacity 
of  5,000  gallons  of  water 
cooled  per  hour  ;  5  b.h.p. 
for  20,000  gallons  and  25 
b.h.p.  for  100,000  gallons. 
Towers  of  concrete  have 
been  built,  one  at  Nurem- 
berg being  named  which 
cools  77,000  gallons  per 
hour. 

Figs.  83  and  84  show  two 
forms  of  fan  tower :  the 
"  Barnard  "  (Fig.  83)  with 
wire-mat  filling,  and  the 
"  Worthington  "  (Fig.  84) 
with  drain  tiles,  over  which 
the  water  is  distributed  by 
a  Barker's  mill. 

It  will  not  usually  pay  to  use  fan  towers  where  there  is 
room  for  natural  draught  towers  to  stand. 

The  Barnard  Tower. — In  the  Barnard  tower  wire  mats  are 
slung  inside.  This  tower  may  be  either  of  the  chimney  or 
fan  type.  The  chimney  type  is  made  as  high  as  70  or  100 
feet,  in  iron,  and  circular  in  plan  or  rectangular.  The  fan 
cooler,  of  course,  may  be  of  more  moderate  total  height. 
The  chimney  cooler  will  reduce  temperature  from,  say,  130° 
to  85°  or  90°.  The  fan  cooler  will  do  more.  The  inside 

263 


FIG.  83.     BABNABD  TOWEB. 


WATER    SOFTENING    AND    TREATMENT 


dimensions  of  Barnard  fan-cooled  towers  are  such  as  to  allow 
about  350  cubic  feet  capacity  per  1,000  gallons  per  hour,  a 
2,000  Ib.  tower  measuring  4  ft.  3  in.  x  5  ft.  2  in.  x  31  ft. 
3  in.  ;  one  of  10,000  gallons  9  ft.  3  in.  x  10  ft.  11  in.  x 
36  ft.  3  in.,  and  one  of  30,000  gallons  16  ft.  3  in.  x  14  ft. 
2  in.  x  41  ft.  4  in.  Fanless  towers  are  of  course  of  greater 

capacity,  a  circular  tower  for 
2,000  Ib.  steam  per  hour  being 
8  ft.  diameter  x  21  ft.  2  in. 
high  from  water-inlet]  level  to 
top  of  foundation ;  a  10,000- 
gallon  tower  measuring  15  ft. 
diameter  x  26  ft.  5  in.  high,  and 
one  of  25,000  gallons  21  ft.  3  in. 
diameter  x  31  ft.  7  in.  high  ; 
dimensions  representing  from 
500  cubic  feet  for  the  smaller 
sizes,  to  450  cubic  feet  for  the 
larger  sizes.  The  fanless  towers 
have  of  course  their  chimney 
height  in  addition  to  the  above 
heights,  which  are  all  measured 
from  the  water  inlet,  and  show 
the  capacity  occupied  by  the 
steel  mats. 

As  regards  all  forms  of  coolers, 
it  may  be  assumed  that  the 
power  necessary  to  pump  the 
water  over  the  tower  is  double 
in  brake  horse-power  the  actual 


•MCTIOM     TANK 


FIG.  84.    WOBTHINGTON  TOWER,    foot  pounds  of   work   done   in 

lifting  the  water   through  the 

height  of  the  water  distribution  above  the  pump.  The 
power  to  drive  the  fans,  as  previously  explained,  is  about 
the  same  as  is  required  to  lift  the  circulating  water,  for  the 
amount  of  air  to  be  moved  is  very  large. 

From  experiments  made  by  Mr.  J.  H.  Vail,1  it  appears 
that  in  a  given  case,  where  non-condensing  engines  used 
1  Trans.  Am.  Soc.  M.E.,  vol.  xx. 
264 


WATER    COOLING 

115,587  Ib.  of  water  per  hour,  it  was  decided  to  add  a  con- 
denser and  tower.  The  tower  selected  was  a  twin  Barnard 
tower,  each  half  12  ft.  3  in.  x  18  ft.  x  29  ft.  6  in.  high,  with 
two  fans.  The  steel  plating  was  ^  in.  and  -J-  in.  with  angle 
stiffeners.  Water  was  delivered  by  a  10-inch  pipe,  extend- 
ing full  length  of  the  apparatus,  slotted  and  provided  with 
96  distributing  pipes.  There  were  42  mats  of  No.  19 
galvanized  wire  woven  to  No.  5  mesh  and  each  mat  was 
15  ft.  6  in.  x  12  ft.,  and  hung  vertically.  The  surface  is 
called  8,064  feet.  It  appears  to  be  7,812  x  2  =  15,624 
as  mere  surface,  not  measuring  it  on  the  wires  them- 
selves. 

The  four  fans  were  8  feet  diameter,  each  equal  at  150  revs, 
to  delivering  90,000  cubic  feet  per  minute,  or  say,  7,000  Ib. 
=  28,000  Ib.  in  all. 

The  rated  capacity  of  each  chamber  per  hour  is  12,500  Ib. 
of  steam  from  132°  F.  to  80°  F.  when  the  atmospheric 
temperature  was  not  over  75°  F.  and  the  humidity  not  over 
85  per  cent.  Under  these  circumstances  28,000  Ib.  of  air 
per  minute  is  provided  for  25,000  Ib.  of  steam  per  hour,  so 
that  approximately  1  Ib.  of  air  is  provided  per  minute  for 
each  pound  of  steam  per  hour.  Put  another  way,  the 
25,000  Ib.  of  steam  bring  about  25,000,000  thermal  units,  or 
say  400,000  units  per  minute.  This  shows  1  Ib.  of  air 
per  14  heat  units,  or  say  1  cubic  foot  of  air  per  heat  unit. 

Previous  figures  show  that  1  cubic  foot  of  air  may  carry 
off  as  many  as  4  heat  units. 

Cooling  is  not  a  matter  of  heating  air  merely,  for  1  Ib. 
of  air  heated  100°  F.  will  only  absorb  about  24  heat 
units,  or  say  2  units  per  cubic  foot.  It  is  the  power  of 
carrying  off  heat  in  a  latent  form  as  vapour  that  adds  to 
the  cooling  effect  of  air.  Thus,  where  1  Ib.  of  air  carries  off 
-^yb.  of  vapour,  the  heat  absorbed  is  -£$  of  1,000,  or  roughly 
50  units.  That  is  to  say,  1  cubic  foot  carries  off  about  4  units 
besides  the  extra  1  to  2  units  due  and  carried  off  by  it  in 
rise  of  temperature. 

Mr.  Vail's  test  figures  are  as  follows  : — 


265 


WATER  SOFTENING  AND  TREATMENT 


Jan.  31. 

Feb. 

June  20. 

July. 

Aug.  26. 

Nov.  4. 

Time       

9  p.m. 

8  p.m. 

8  p.m. 

8  p.m. 

8  p.m. 

5.35 

Atmospheric     tempera- 

- \ 

ture       

30° 

36° 

78° 

96° 

65° 

59° 

Condenser  discharge    . 

110° 

110°       120° 

130° 

118° 

129° 

Condenser  suction 

65° 

84°    !    84° 

93° 

88° 

92° 

Temperature  reduction 

45° 

26° 

36° 

37° 

30° 

37° 

Fan-speed     revs,     per 

min  

36 

0 

145 

162 

150 

148 

Condenser  vacuum 

251 

26 

25 

241 

251 

25 

Strokes  of  air  pump    . 

30 

30 

37 

44 

43 

28 

On  one  occasion  the  plant  was  worked  fourteen  hours  in 
an  atmospheric  temperature  between  83°  F.  and  103°  F. 
The  condenser  discharge  varied  between  106°  and  128°,  the 
suction  from  91°  to  98°  F.  The  average  fan  speed  was  150 
r.p.m.  and  the  vacuum  varied  between  20  in.  and  26  in., 
with  the  air  pump  running  38  to  50  strokes. 

The  power  developed  varied  between  400  and  900  i.h.p. 

In  the  month  of  November  a  25-inch  vacuum  gave  out  of 
a  total  of  643-3  h.p.,  no  less  than  185  i.h.p.  below  the 
atmospheric  line,  so  that  allowing  for  previous  back  pressure 
at  least  200  h.p.  must  have  come  from  the  condenser.  It 
required  13*75  h.p.  to  drive  the  air  pump  ;  13«5  h.p.  to 
drive  the  fan,  showing  a  balance  of  173  h.p.  from  the  plant 
to  pay  for  interest  and  depreciation,  etc. 

It  may  be  added  that  since  cooling  towers  have  been  rated 
largely  on  American  experience  with  air  considerably  dryer 
and  therefore  more  refrigerative  than  is  the  case  in  England 
they  will  not,  for  a  given  size,  give  equal  results  in  moister 
climates,  and  engineers  should  calculate  them  not  on  what 
has  been  done  elsewhere,  but  on  the  basis  of  the  conditions 
under  which  they  will  have  to  work  and  on  a  basis  of  thermal 
unit  capacity  throughout. 

It  is  open  to  be  assumed  that  in  foggy  weather,  the  air 
being  sometimes  fully  saturated  with  moisture,  there  can 
be  little  cooling  effect  by  the  air  upon  warm  water,  either 
in  a  tower  or  otherwise.  This  superficial  view,  however, 
ignores  the  facts  in  the  above  table.  Far  more  moisture  is 

266 


WATER    COOLING 


required  to  saturate  air  when  warm  than  when  cold,  and  the 
mere  fact  of  raising  the  temperature  of  the  air  in  its  passage 
by  so  much  hot  water  is  enough  largely  to  increase  its 
capacity  for  moisture. 

Further,  periods  of  fog,  more  especially  perhaps  in  the 
south-east  of  England,  are  periods  of  low  temperature.  A 
London  fog  is  very  usually  accompanied  by  frost.  The 
atmosphere,  it  is  true,  is  saturated  with  moisture  at  such 
times,  but  it  is  also  true  that  not  very  much  moisture  is 
sufficient  to  do  this.  There  is  therefore  no  need  to  fear 
the  serious  failure  of  a  cooling  tower  during  fog.  It  is,  how- 
ever, desirable,  in  the  case  of  large  towers,  to  divide  the  fan 
equipment  into  two,  three,  or  even  more  separate  items,  in 
order  that  the  amount  of  air  blown  may  be  regulated.  The 
fans  are  merely  air  propellers,  serving  to  move  a  large  volume 
of  air  against  a  low  resistance. 

Spraying  Nozzles. 

Spraying  nozzles  are  small  gun-metal  nozzles  fitted  inside 
with  little  loose  spirals  of  flat  sheet  brass  or  with  a  screw  of 
the  form  shown  in  Fig.  85,  which  is  that  of  Ledward  &  Co. 

These  nozzles  are  fitted  in  large  num- 
bers on  a  length  or  lengths  of  pipe  at 
any  height  above  ground.  The  air-pump 
or  circulating-pump  discharge  escapes 
through  them  and  is  flung  into  the  air 
with  a  whirling  motion  which  causes  it  to 
break  up  into  spray.  The  pressure  must 
not  be  too  great,  or  too  much  resistance 
will  be  thrown  on  the  pump.  A  head  of 
10  feet  is  considered  suitable,  and  the 
annexed  table  (XXV.)  gives  the  output  at 
that  pressure.  Sprayers  must  be  used 
with  judgment  and  cannot  be  placed 
high  when  near  other  property,  as  the 
wind  carries  the  spray  and  causes  a  public 
nuisance.  In  such  cases  they  must  be  placed  low  and  may 
be  arranged  over  an  area  of  concreted  floor  sloped  to  drain 
the  water  back  to  the  suction  point.  It  is  not  necessary 

267 


FIG.  85.    SPRAY 
NOZZLE. 


WATER  SOFTENING  AND  TREATMENT 

to  work  them  by  the  air  pump.  They  can  of  course  be 
worked  by  their  own  special  pump,  and  where  water  is 
scarce  and  space  insufficient  sprayers  may  be  run  by  a 
small  electrically  driven  pump  to  keep  water  in  circulation 
constantly,  cooling  it  down  during  hours  of  light  load. 


TABLE  XXV. 

SPRAYER  OUTPUT. 


Diameter 

Diameter  of 

Approximate  Discharge 

No. 

of 
Orifice. 

Supply 
Pipe. 

per  hour  under  10  ft 
head  gallons. 

1 

Jin. 

2  in- 

90 

2 

iin. 

lin. 

350 

3                  fin. 

l£in. 

800 

4                  lin. 

2  in. 

1400 

268 


Section  V 

FEED   PUMPS 
INJECTORS 


269 


CHAPTER  XXVII 
FEED  PUMPS 

IT  is  impossible  to  include  descriptions  of  more  than  a 
fraction  of  the  feed  pumps  on  the  market.  A  few 
only  can  be  described  in  the  limited  space  available.  Feed 
pumps  exist  as  direct  acting,  steam  driven,  with  steam  and 
water  cylinders  tandem  fashion  on  the  one  rod.  as  crank- 
shaft pumps  also  steam  driven,  electrically  driven  pumps, 
belt-driven  pumps,  etc. 

In  dealing  with  the  subject  generally  engineers  should  be 
cautious  how  they  use  the  tables  of  horse-power  and  pump 
duty  which  appear  in  American  catalogues,  many  of  which 
are  widely  scattered  in  this  country.  These  tables  are  often 
based  on  a  gallon  of  only  8J  Ib.  and  not  on  the  imperial 
gallon  of  10  Ib.,  and  the  effect  when  this  is  not  recognized 
is  unfair  to  the  English  pump  maker,  for  the  tables  convey 
a  false  idea  of  what  is  done  by  other  pumps. 

A  pump  is  really  a  simple  matter  to  calculate,  for  it  is 
merely  a  machine  for  raising  weights,  or  for  moving  a  piston 
against  a  pressure  that  can  be  translated  into  the  equivalent 
of  a  raised  weight.  Large  masses  of  water  are  often  put 
into  movement  by  small  pumps,  for  supply  pipes  are  some- 
times long.  It  is  an  axiom  in  durable  and  good  pump 
practice  that  speeds  shall  be  slow  where  movement  is  of  the 
reciprocating  order,  while  the  contrary  holds  good  where 
the  water  moves  continuously  and  in  one  direction,  as  in 
the  case  of  the  centrifugal  pump  and  other  perhaps  less 
known  forms.  When  reciprocating  pumps  do  run  quickly 
they  are  of  special  design  in  which  provision  is  made  for 
the  preservation  of  motion  of  the  water  in  one  continuous 
flow. 

Care  must  be  taken  in  choosing  a  pump  carefully  to 

271 


WATER    SOFTENING   AND    TREATMENT 

compare  speeds  and  capacities,  as  pumps  are  very  variously 
rated,  and  it  is  bad  practice  to  economize  by  using  cheap 
pumps  at  high  speeds.  The  exhaust  from  steam-driven 
pumps  should  be  utilized  to  heat  feed  water,  and  may  be 
made  specially  useful  where  softening  by  the  Porter-Clark 
process  is  carried  on,  the  exhaust  steam  helping  the  process 
very  materially. 

Where  a  pump  draws  its  supply  from  a  distance  there 
ought  to  be,  near  the  pump,  an  air,  or  rather  partial  vacuum 
chamber,  as  a  reserve  to  maintain  constant  flow  in  the 
suction  pipe  and  avoid  shock. 

It  is  usual  to  have  feed  apparatus  in  duplicate  as  a  safe- 
guard against  breakdown,  and  it  is  very  convenient  for 
testing  purposes  to  be  able  to  feed  any  one,  or  more,  boilers 
from  one  source,  so  that  the  water  supply  to  those  particular 
boilers  can  be  separately  measured  ;  but  an  undue  duplica- 
tion of  feed  pipes  should  be  avoided,  breakdown  being 
guarded  against  rather  by  wise  expenditure  on  good  pipes, 
flanges  and  joint  rings,  than  by  a  prolific  use  of  inferior 
material. 

When  hot  water  is  to  be  pumped  it  should  either  flow  by 
gravity  to  the  pump,  or  the  height  of  lift  should  be  con- 
siderably less  than  that  represented  by  25  feet  —  h,  where 
h  is  the  height  in  feet  of  a  column  of  water  equivalent  to 
the  pressure  of  steam  at  the  given  temperature. 

Thus  at  a  temperature  of  162°  F.  the  head  in  feet  is  about 
12.  Then  25  —  12  =  13  feet  would  be  the  maximum  lift 
that  should  be  attempted. 

The  actual  net  work  done  by  a  feed  pump  is  represented 
by  the  product  of  the  weight  of  water  pumped  in  a  given 
time,  and  the  height  in  feet  equivalent  to  the  boiler  pressure 
against  which  the  feed  is  pumped.  Pump  efficiency  may 
be  assumed  at  50  per  cent.,  or  say  at  40  per  cent,  overall 
efficiency  for  pump  and  electric  motor,  as  ascertained  by 
the  writer  in  case  of  a  treble  ram  pump  electrically  driven 
by  worm  gearing.  Where  worm  gear  is  employed  the 
thrust  bearing  should  be  long  and  run  in  an  oil  bath,  and 
the  thrust  collar  should  not  be  placed  in  too  narrow  a  part 
of  the  casing  or  it  will  fail  to  get  sufficient  lubrication. 

2J2 


FEED    PUMPS 

In  the  following  tables  (XXVI.  and  XXVII.)  are  given  a 
few  particulars  as  to  the  lift  practically  advisable  for  pumps 
drawing  hot  water.  The  table  is  worked  out  for  barometric 
pressures  at  different  altitudes,  but  in  place  of  the  baro- 
metric pressure  may  be  placed  14-7  less  the  vapour  tension 
of  water  at  any  given  temperature,  as  shown  in  Table  XIII 

It  is  also  useful  to  remember  that  the  square  of  the 
diameter  in  inches  of  a  cylindrical  pipe  gives  approximately 
the  weight  of  water  it  contains  per  yard  in  pounds. 


TABLE  XXVI. 

FOR  CONVERTING  FEET  HEAD  OF  WATER  INTO  PRESSURE  PER  SQUARE 

INCH. 


'    Feet 
Head. 

Pounds  per 
Square  Inch. 

Feet 
Head. 

Pounds  per 
Square  Inch. 

Feet 
Head. 

Pounds  per 
Square  Inch. 

1 

•43 

55 

23-82 

190 

82-29 

2 

•87 

60 

25-99 

"200 

86-62 

3 

1-30 

65 

28-15 

225 

97-45 

4 

1-73 

70 

30-32 

250 

108-27 

5 

2-17 

75 

32-48 

275 

119-10 

6 

2-60 

80 

34-65 

300 

129-93 

7 

3-03 

85 

36-81 

325 

140-75 

8 

3-40 

90 

38-98 

350 

151-58 

9 

3-90 

95 

41-14 

375 

162-41 

10 

4-33 

100 

43-31 

400 

173-24 

15 

6-50 

100 

47-64 

500 

216-55 

20 

8-66 

120 

51-97 

600 

259-85 

25 

10-83 

130 

56-30 

700 

303-16 

30 

12-99 

140 

60-63 

800 

346-47 

35 

15-16 

150 

64-96 

900 

389-78 

40 

17-32 

160 

69-29 

1000 

433-09 

45 

19-49 

170 

73-63 





50 

21-65 

180 

77-96 

— 

— 

Thus  a  4-inch  pipe  contains  1-6  gallons  =  16  Ib.  =  (4  x  4). 

To  find  the  pressure  in  pounds  to  the  square  inch  of  a  column  of 
water,  multiply  the  height  of  the  column  in  feet  by  -434.  Approxi- 
mately, every  foot  elevation  is  equal  to  one-half  pound  pressure  to  the 
square  inch  ;  this  allows  for  ordinary  friction. 

The  mean  pressure  of  the  atmosphere  is  usually  estimated  at  14- 7 

273  T 


WATER  SOFTENING  AND  TREATMENT 


pounds  to  the  square  inch,  so  that  with  a  perfect  vacuum  it  will 
sustain  a  column  of  mercury  29'9  inches,  or  a  column  of  water  33*9 
feet  high. 

Doubling  the  diameter  of  a  pipe  increases  its  capacity  four  times. 
Friction  of  liquids  in  pipes  increases  as  the  square  of  the  velocity. 

TABLE  XXVII. 

FOB  CONVERTING  PRESSURE  PER  SQUARE  INCH  INTO  FEET  HEAD 

OF  WATER. 


Pounds  per 
Square  Inch. 

Feet 
Head. 

Pounds  per 
Square  Inch. 

Feet 
Head. 

Pounds  per 
Square  Inch. 

Feet 
Head. 

1 

2-31 

55 

126-99 

180 

415-61 

2 

4-62 

60 

138-54 

190 

438-90 

3 

6-93 

65 

150-08 

200 

461-78 

4 

9-24 

70 

161-63 

225 

519-51 

5 

11-54 

75 

173-17 

250 

577-24 

6 

13-85 

80 

184-72 

275 

643-03 

7 

16-16 

85 

196-26 

300 

692-69 

8 

18-47 

90 

207-81 

325 

750-41 

9 

20-78 

95 

219-35 

350 

808-13 

10 

23-09 

100 

230-90 

375 

865-89 

15 

34-63 

110 

253-98 

400 

922-58 

20 

46-18 

120 

277-07 

500 

1154-48 

25 

57-72 

125 

288-62 





30 

69-27 

130 

300-16 

— 

— 

35 

80-81 

140 

323-25 

— 

— 

40 

92-36 

150 

346-34 

— 

— 

45 

103-90 

160 

369-43 





50 

115-45 

170 

392-52 

— 

— 

WEIGHT  AND  CAPACITY  OF  DIFFERENT  STANDARD  GALLONS  OF 

WATER. 


Cubic 

Weight  of  a 

Gallons 

Inches 
in  a  Gallon. 

Gallon  in 
Pounds. 

in  a 
Cubic  Foot. 

Weight  fcpf  a 
cubic  foot  of 

I 

water,  English 

Imperial  or 

standard 

English 

277-274 

10-00 

6-232102 

62-321    Ib. 

United    States 

231- 

8-33111 

7-480519 

Avoirdupois. 

274 


FEED    PUMPS 


CO  O  t-  CO  O  CO 

coco^^^r^-^»o»o»oIc>»ccoco«boF-i> 
P          'J       co       •*       S       -       '^       "^       '^       ' 

PHI— 'i— (i— ii— ii— ((MCNOiO^^^^OlcoCOWcO 

>  §     s 

X£  ^H^Hr-H_P-H^H^OJ^i 

9  S 

m     "< 

™  § 

H     ^         < 

g     l^^_^^^^^^ 

I 

q 


<M  CO 


275 


WATER    SOFTENING    AND    TREATMENT 


p 

3 

w 

H 

I  1 

>    & 

B  * 

<3?     pt, 

W    o 


a?    O 

ft    o 
p     t) 


w 


o 

,_,  -P 


.03 


•I 


©  „    ^    ^ 

j>  *  *  s 

o  o  o  o 

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i— i  <N  CO  »O 


276 


FEED    PUMPS 

Flow  of  water  in  pipes. — It  is  not  desirable  to  give  too 
rapid  a  velocity  to  water  flowing  in  a  pipe.  About  3  feet 
per  second  is  considered  a  sufficient  velocity. 

Darcy's  formula  for  the  loss  of  head  due  to  friction  in 
pipes  is  :— - 

0-0000208 16\ 

-    \ 


-»  r  ,-%.      r-v  ••    ^  «.  ^  ,-k          •         V7WJ.WVH.J  .  "  Trt 

h=[   0-017379+ d2  ]x 

\  d 


d 


- 

-  / 

/ 

(1)         and 


/t=(Voi98920  +  °-00166573)J-^-      (2);    where 
V  d         /  d  2g 

h  =  loss  of  head  in  feet  due  to  friction. 
d  =  internal  diameter  of  pipe  in  feet. 
v  =  velocity  per  second  in  feet. 
I   =  length  of  pipe  in  feet. 
2g  =  64  324. 

The  formula  (1)  is  used  for  velocities  less  than  0*33  feet 
per  second,  and  should  fit  feed-pipe  work  if  very  liberally 
proportioned. 

Formula  (2)  is  for  v  =  more  than  0-33  feet  per  second. 

The  rules  are  applicable  to  pipes  of  4  in.  and  upwards, 
and  represent  about  10  feet  loss  of  head  per  1,000  feet  for 
4-inch  pipes  at  3  feet  per  second. 

For  smooth  inside  pipes  of  small  diameter  Weston's 
formula  is  : — 


oi26  + 

Vv  /   d   2g 

By  this  rule  a  1-inch  pipe  will  lose  about  5  feet  of  head 
per  100  feet  for  a  velocity  of  3  feet  per  second,  whereas  a 
2-inch  pipe  will  only  lose  about  2  J  feet  of  head  per  100  feet. 
Loss  of  head  increases  with  the  square  of  the  velocity,  and 
the  influence  of  length  is  serious.  Velocity  may  be  in- 
creased for  short  distances  in  larger  sizes  of  pipes  up  to 
6  feet  per  second. 

Long  pipes  laid  horizontally  to  pumps  should  have  a 
suction  air  vessel  near  the  pump  to  assist  in  preserving 

277 


WATER    SOFTENING    AND    TREATMENT 


the  motion  of  the  water  uniform  in  the  pipe,  and  every 
pump  should  have  an  air  vessel  on  its  delivery  side. 

In  fixing  on  feed-pump  arrangements,  it  is  always  de- 
sirable that  there  should  be  at  least  two  feed  pumps  to  a 
plant.  Where  a  large  plant  is  divided  into  a  number  of 

independent  sections,  it  is  a 
doubtfully  good  practice  to  pro- 
vide each  set  or  section  with  so 
much  provision  in  the  way  of 
feed  pumps.  In  such  a  case  a 
moderate  supply  of  spares  should 
suffice,  all  the  pumps  discharging 
into  one  feed  main,  which  may 
have  cut-out  valves  to  divide 
off  the  various  sections.  By 
this  means  the  failure  of  the 
pump  or  pumps  of  any  section 
can  be  made  good  by  a  supply 
through  the  common  main. 
Speaking  generally,  the  same 
may  be  said  of  feed  pipes  as 
of  steam  pipes,1  that  an  excel- 
lence of  materials  and  construc- 
tion should  be  preferred  to  an 
excessive  duplication  of  mains. 

The  Weir  Feed  Pump,  of 
which  a  simple  form  is  shown 
in  Fig.  86,  is  one  of  the  slow  and 
long-stroke  variety,  built  for 
economy,  durability  and  relia- 
bility. 

From  the  annexed  tabje  it 
will  be  seen  that  at  the  normal 

speed  of  practically  16  double  strokes  per  minute,  the  stroke 
being  15  in.,  the  piston  velocity  is  only  40ft.  per  minute. 
The  pump  tested  had  6-in.  pump  cylinder  and  8-in.  steam 
cylinder,  a  stroke  of  15  in.,  and  a  steam  pressure  of  110  and 
107  Ib.  In  the  course  of  twelve  tests  the  efficiency  never 

1  See  Steam  Pipes,  by  the  same  Author,  Constable  &  Co. 

278 


FIG.  86.     WEIR  FEED  PUMP. 


FEED    PUMPS 

fell  below  95  per  cent.,  even  at  so  slow  a  speed  as  three 
double  strokes  per  minute.  Pumps  like  these  have  a  margin 
very  considerable,  when  it  is  considered  that  a  bucket 
velocity  of  80  to  100  ft.  per  minute  is  considered  quite 
ordinary. 

Normal  Speed.     Slow  Speed. 
Steam  pressure  at  pump 110  Ib.  107  Ib. 


Water  „  „          :      ....  164  Ib. 

Double  strokes  per  minute      ....  15-9 

Efficiency  of  pump 97-25% 

Pounds  of  water  per  pound  of  steam  .      .  84-6 

Pounds  of  steam  per  net  h.p 63*1 

Foot-pounds  work  per  B.Th.U.  to  212°    .  31-1 


164  Ib. 

6-0 

96-6% 
55-3 
95-3 
21-0 


The  exhaust  from  a  Weir  or  any  other  steam-driven 
pump  may  be  turned  through  the  intermediate  receiver 
of  a  compound  engine  or  used  in  a  feed  heater.  The  former 
use  is  preferable  as  a  rule.  The  valve  of  the  Weir  pump  is 
a  D  valve,  on  the  back  of  which  works  a  small  auxiliary 
valve,  and  the  design  is  such  that  when  steam  is  turned  on 
the  pump  will  always  work.  The  barrel  is  of  gun  metal, 
the  rod  of  bronze,  and  so  are  the  valves  and  seats,  water 
piston  and  mountings.  These  pumps  work  up  against 
pressures  of  200  Ib.,  and  have  been  made  even  to  work  at 
600  Ib. 

The  makers  publish  the  annexed  table  of  quantities  and 
floor-space  allowances  as  a  guide  in  making  provision  for 
pumps.  The  quantities  in  Table  XXX.  may  be  reduced  by 
5  per  cent.,  as  an  allowance  for  slip  or  other  loss. 

The  advantage  of  a  direct-acting  steam  pump  is,  of  course, 
that  the  application  of  the  moving  force  to  the  water  is 
elastic,  and  there  can  be  no  excess  of  mechanical  stress 
exerted  in  any  part  of  the  pump,  all  stresses  in  which  are 
limited  to  the  maximum  static  steam  stress  on  the  steam 
piston. 


279 


WATER    SOFTENING   AND    TREATMENT 


TABLE  XXX. 

STANDARD   SIZES  AND   CAPACITY  OF  WEIR  DIRECT-ACTING   PUMP 
FOR  LAND  INSTALLATIONS. 


1  Gallons 

Dia- 
meter 
of 
Pump. 

Cylin- 
der of 
Pump. 

Length 
of 
Stroke. 

Gallons 
Discharged 
per 
Double 
Stroke. 

Discharged 
per  Hour 
at  12 
Double 
Strokes 

Floor  Space. 

Height. 

per  Min. 

in. 

in. 

in. 

ft.     in.     ft.   in. 

ft.    in. 

6f 

7J 

15 

2-49 

1792-8 

1      5|  X  1      7 

6     4| 

6 

8 

15 

2-94 

2206-8 

1      9|xl    10 

6  10 

6 

8 

18 

3-53 

2541-6 

1      91x1    10 

7     7 

7 

9* 

18 

4-86 

3499-2 

1    10    X2     0 

7     7 

7 

9* 

21 

5-67 

4082-4 

1    10    X2     0 

8     4 

8 

101 

18 

6-352 

4573-4         1     2    x2     3 

8     0 

8 

10J 

21 

7-43 

5349-6         2     2x2     3 

8     9 

8 

ioi 

24 

8-49 

6113-8         2     2    x2     3 

9     6 

9 

12 

21 

9-34 

6724-8         2     4    x2     6 

8     9 

9 

12 

24 

10-67 

7682-4         2     4    x2     6 

9     6 

91 

12* 

24 

11-83 

8521-2         2     4    x2     6 

9     6 

D'irecting-Acting  Steam  Pumps. 

There  is  a  large  class  of  direct-acting  steam  pumps  of 
the  duplex  and  other  varieties,  which  have  perhaps  the 
advantage  of  small  initial  cost,  but  are  not  always  very 
strongly  built.  They  are  often  found  with  excessively  light 
valve  spindles,  and  are  not,  when  of  foreign  origin,  usually 
up  to  the  standard  looked  for  in  an  English-made  pump. 
In  the  duplex  type  the  valve  gear  of  the  one  side  is  driven 
from  the  piston  rod  of  the  other  side,  and  vice  versa.  In 
purchasing  these  pumps  they  are  sometimes  found  to  have 
a  catalogue  rating  on  so  many  gallons  per  hour,  and  the 
gallon  is  very  much  less  than  the  English  imperial  gallon 
of  10  Ib.  of  water.  Errors  are  apt  to  arise  from  this  catase. 

Worthington  Vertical   Duplex  Feed   Pump. 

This  pump  of  the  long-stroke  variety  (Fig.  84)  has  steam 
cylinders  14  in.  diameter,  pump  plungers  9J  in.  diameter, 


1  This  is  the  best  speed  for  boiler  feeding. 
280 


FEED    PUMPS 


and  18  in.  stroke.  Continuity  of  action  is  secured  by  driving 
each  steam  valve  from  the  rod  of  the  other  cylinder,  as 
customary  in  duplex  pumps. 


FlG.    87.       WORTHINGTON    LONG-STROKE    DUPLEX   FEED    PUMP. 

Flywheel  Pumps. 

The  "  Cameron  "  class  of  pumps,  steam-driven  and  with 
ram  pump,  is  still  a  favourite  pump  with  many  steam  users, 

281 


WATER  SOFTENING  AND  TREATMENT 

and  is  largely  employed  in  the  textile  mills  for  both  boiler- 
feed  and  fire  purposes.  Above  80  Ib.  pressure,  double-ram 
pumps  are  employed  for  steadiness.  These  pumps  are  very 
durable.  An  air  vessel  is  necessary,  and  this  is  amply  pro- 
vided for  by  the  cast-iron  columns  of  the  framing,  which  are 
hollow.  Fig.  88  shows  one  of  these  pumps  as  made  by 


FIG.  88.     CAMERON  OB  FLYWHEEL  PUMP  (Pearn). 

Frank  Pearn  &  Co.,  and  the  following  table  gives  some 
particulars  of  their  capacity  when  double.  The  single- 
ram  pumps,  with  single  steam  cylinder,  have  a  capacity 
one-half  that  of  the  double-ram  pumps  of  equal  jam 
diameter. 

When  carefully  packed  these  pumps  run  easily,  and  have 
a  good  volumetric  efficiency. 


282 


FEED    PUMPS 


TABLE  XXXI. 
DIMENSION  AND  CAPACITY  OF  DOUBLE-RAM  CAMERON  PUMPS. 


Diam.  of  Rams  .  .  in. 

2 

2* 

3 

H 

4 

*i 

5 

Diam.     of    Cylin- 

ders.     .      .   in. 

4 

5 

6 

6 

7 

7 

7 

Length  of  Stroke 

in. 

3 

4 

5 

5 

6 

6 

6 

Strokes  per  Minute 
Gals,  per  Hour 

130 
520 

100 
800 

90 
1340 

90 

1800 

80 
2560 

80 
3200 

80 
4000 

Diam.  of  Suet,  and 

Del.  .      .      .in. 

H 

1J 

2 

2 

3 

3 

3 

Diam.     of    Steam 

Pipe.       .      .   in. 

f 

1 

1 

u 

U 

U 

li 

Diam.  of  Exhaust 

Pipes      .      .   in. 

1 

1 

1 

1 

U 

n 

It 

Diam.  of  Rams  in. 

6 

7 

8 

10 

12 

15 

Diam.     of    Cylin- 

ders       .      .   in. 

Si 

10 

12 

14 

16 

18 

Length  of  Stroke 

in. 

8 

9 

10 

m 

15 

15 

Strokes  per  Minute 

70 

60 

54 

47 

40 

35 

Galls,  per  Hour    . 

6400 

8800 

11500 

20000 

28800 

40000 

Diam.  of  Suet,  and 

Del.      .      .      in. 

4 

4 

5 

6 

8 

— 

Diam.     of    Steam 

Pipe       .      .   in. 

2 

2 

2* 

3 

4 

— 

Diam.  of  Exhaust 

Pipes     .      .   in. 

2 

2 

2| 

3 

4 

— 

The  Fromentin  Boiler  Feeder. 

Though  rarely  seen,  this  apparatus  has  been  found  to 
work  well,  and  it  should  do  so  with  clean  water,  though 
there  may  be  a  reasonable  doubt  of  its  action  when  water 
contains  carbonate  of  lime  and  is  already  heated  to  deposit- 
ing point.  The  apparatus  consists  of  two  iron  bottles  on  a 
balance  beam,  so  arranged  that  each  bottle  in  turn  is  open 
to  the  water  supply  and  the  boiler  alternately.  A  bottle 
full  of  water  cannot  run  out  into  the  boiler  until  the  end 
of  the  discharge  pipe  in  the  boiler  has  become  exposed  by 
lowering  of  the  water  level. 

283 


WATER    SOFTENING    AND    TREATMENT 


EXHAUST   STEAM 


The  Injector. 

The  Injector  is  not  an  efficient  machine  as  a  heat 
engine,  but  it  serves  the  double  purpose  of  a  feed  pump 
and  a  feed  heater,  and  returns  the  heat  it  does  not  utilize 
to  the  boiler,  though  not  at  maximum  boiler  temperature, 
and  thus  at  a  loss  of  efficiency. 

Injectors  will  drive  water  into  the  boiler  from  which  their 

supply  of  steam  is  taken.  They 
will  even  work  against  higher 
pressures. 

The  exhaust  steam  injector 
using  steam  at  atmospheric  pres- 
sure will  even  deliver  water,  if 
supplied  cold,  into  a  boiler  at 
possibly  100  Ib.  pressure. 

The  action  of  the  injector  is 
simple,  and  resolves  itself  into  a 
question  of  momentum. 

One  pound  of  steam  cooled  to 
1 80°  F.  will  part  with  about  1,000 
B.Th.U.  If  water  be  supplied  at 
60°  F.  and  heated  to  180°  F.,  it 
will  gain  120°  F.,  so  that  8  Ib.  of 
water  would  in  such  a  case  con- 
dense 1  Ib.  of  steam  to  water  at 
180°F.  ;  and  if  the  velocity  of 
flow  of  the  steam  were  900  feet 

per  second,  the  velocity  of  the  combined  jet  would  be  900  4- 
(8  +  1)  —  100  feet  per  second.  Now,  a  velocity  of  100  feet 
per  second  will  result  from  a  head  of  H  feet  of  water  by  the 
customary  formula  :  V  =  8  H,  whence  H  =  about  150, feet 
or  64 J  Ib.  The  above  figures  are  illustrative  merely,  for 
it  is  generally  understood  that  the  exhaust  injector  will 
save  more  than  an  eighth  of  the  exhaust  steam,  an  economy 
of  15  to  20  per  cent,  being  claimed.  Makers  of  these 
instruments  state  that  they  will  heat  the  feed  to  190°  F., 
and  inject  it  into  a  boiler  up  to  75  Ib.  pressure.  The  action 
of  this  injector  is  secured  by  splitting  the  combining  nozzle 

284 


REGULATOR  — 


FIG.  89.     EXHAUST  STEAM 
INJECTOR. 


FEED    PUMPS 


in  half  longitudinally, 
and  hinging  the  loose 
half  so  that  the  injec- 
tor standing  vertically 
the  flap  can  freely 
swing  open  and  as 
easily  close  when  a 
vacuum  is  again  made 
within  it. 

The  construction  is 
clear  in  Fig.  89. 

For  pressures  above 
75  Ib.  the  jet  from  the 
exhaust  injector,  at 
say  70  Ib.,  passes  on  to 
a  live  steam  injector, 
as  in  Fig.  90. 

Water  at  190°  F. 
will  condense  more 
steam  at  a  high  pres- 
sure which  heats  the 
feed  now  to  270°  F., 
at  which  temperature 
it  enters  the  boiler. 

Fig.  90  shows  the 
form  of  combined  in- 
jector suited  for  loco- 
motive work. 

Both  portions  are 
fitted  with  the  split 
nozzle,  which  gives 
automatic  re-starting. 
The  size  of  an  in- 
jector is  always  the 
smallest  diameter  of 
the  cones  in  milli- 
metres. 

The  number  of  gal- 
lons per  hour  that  can 


WATER    SOFTENING   AND    TREATMENT 


be  fed  by  an  ordinary  live-steam  injector  varies  with  the 
square  of  the  diameter  of  throat  in  millimetres,  and  with 
the  square  root  of  the  steam  pressure,  if  published  tables 
are  to  be  relied  on.  The  apparent  formula  is  G  =  D2  x 
2  yP,  where  G  =  gallons  per  hour  and  P  =gauge  pressure 
of  steam. 

Thus  a  No.  2  is  rated  at  25  gallons  for  10-lb.  and  100 
gallons  for  160-lb.  pressure.  A  No.  20  is  rated  at  2,513  and 
10,048  gallons  respectively  for  the  same  two  pressures. 
Other  sizes  and  other  pressures  all  are  consistent. 

All  injectors  fixed  "  lifting  "  give  a  less  delivery  according 
to  the  height  of  the  life.  A  slight  lift,  such  as  3  feet,  makes 
very  little  difference  ;  but  with  higher  lifts  the  reduction  is 
about  as  follows  : — 

A  lift  of  6  feet  reduces  the  delivery  about  10%. 
„       12  feet         „  „  „      25%. 

„       18  feet         „  „  „      35%. 

There  are  an  almost  infinite  variety  of  injectors,  many 

of  them  of  apparently 
unnecessary  complication 
of  parts. 

Every  information  as 
to  fitting  and  capacity 
will  be  found  in  makers' 
catalogues. 

It  may  be  added  that 
injectors  should  always 
draw  their  supply  of 
water  through  a  carefully 
made  fine  wire-gauze 
strainer,  and  that  when 
the  internal  parts  ^  be- 
come coated  with  scale 
they  can  be  cleansed  by 
soaking  in  a  10  per  cent, 
solution  of  hydrochloric 
acid.  When  fitted  to 
lift  their  supply,  the 
capacity  of  injectors  is 
reduced. 


STEAM 


WATER 


OVERFLOW 


DELIVERY 


FIG.  91.     EXHAUST  STEAM  INJECTOB 
(Holden  &  Brooke). 

286 


FEED    PUMPS 

The  reduction  of  capacity  is  nearly  2  per  cent,  per  foot 
of  lift,  and  the  maximum  lift  is  about  1 8  feet,  and  the  suction 
pipe  should  have  a  foot  retaining  valve. 

The  steam-supply  pipe  to  all  injectors,  and  especially  to 
exhaust-steam  injectors,  should  be  taken  off  the  steam  pipe 
by  a  square  bend,  in  order  that  moisture  and  oil  may  be 
separated  out  of  the  steam.  Where  non-condensing  engines 
are  employed,  an  exhaust  injector  offers  a  means  of  heating 
the  feed- water  tank  and  assisting  the  softening  process. 
Considering  the  absence  of  serious  or  perhaps  any  pressure 
against  which  it  may  have  to  work,  it  is  probable  that  such 
an  injector  could  even  be  employed  to  draw  its  steam  from 
the  exhaust  pipe  of  a  condensing  engine  for  warming  up  a 
feed  tank.  In  such  a  case  possibly  it  would  be  found 
necessary  to  connect  the  overflow  of  the  injector  to  the 
condenser,  with,  of  course,  a  non-return  valve  in  circuit. 

A  rule  sometimes  used  for  finding  the  velocity  of  flow  of 
steam  is  : — 


( 
P  =  pressure  per  square  foot  and  R  =  weight  of  a  cubic 


V  —  8\     —         P  W     where  W  is  the  volume  of  one 
1 


/      n  P 

—  8\/  where  V  =  feet  per  second  velocity. 

v     (n  +  I )  R 

=  pressure  per  square  foot  and 
foot  of  steam  at  the  pressure  P  ;   or 

=  H/— 

v    n  + 
pound  of  steam  in  cubic  feet, 

n  =  1  to  1-4,  according  to  dryness. 

Approximately  V  =  6\/ —     the  true  value  of  V  being 

some  5  per  cent,  less  for  wet  steam  and  2  per  cent,  greater 
for  dry  steam. 

The  following  table  gives  the  capacity  and  sizes  of  some 
plain  exhaust  injectors. 


287 


WATER  SOFTENING  AND  TREATMENT 


TABLE  XXXII. 

SIZES  AND  CAPACITIES  OF  EXHAUST  STEAM  INJECTORS. 


Inside  Diameter  of  Pipes. 

Size  of 
Injector, 
mm. 

Delivery  in 
gallons 
per  hour. 

/ 

Branch  from 
Exhaust. 

Water  Pipes. 

Overflow. 

3 

150 

l£in. 

fin. 

|in. 

4 

270 

2  in. 

lin. 

fin. 

5 

420 

2  in. 

1  in. 

1  in. 

6 

600 

2£m. 

IJin. 

Ijin. 

7 

830 

3  in. 

Urn. 

li  in. 

8 

1080 

3|  in. 

ijin. 

l£in. 

9 

1370 

4  in. 

li  in. 

if  in. 

10 

1700 

4^  in. 

2  in. 

2  in. 

11 

2050 

5  in. 

2  in. 

2  in. 

12 

2450 

5|in. 

2£  in. 

2  in. 

TABLE  XXXIII. 

TEMPERATURE  OF  FEED  WATER,  HEIGHT  OF  LIFT,  ETC.,  FOR  "SiRius" 
SELF-ACTING  INJECTORS. 


Boiler  Pressure. 

Height  Injector                         2  Temperature  at  which 
will  lift                             Injector  will  take  feed  water 

its  feed  water. 

(fixed  non-lifting). 

1  25  Ib. 
30 

j        5  to   12  feet. 

150°  F. 

NOTE  :  —  If  fixed 
"  lifting,"  the  maxi- 

35 

(See  Dimension  A, 

ISO0 

mum    temperature 

80 

Fig.  146.)                     \    :;:"      " 

I      12  to  20  feet. 

of  the    feed    water 
must  be   5°  to   10° 

100 

j 

125°  „ 

less     according     to 

150 

105°  „ 

height. 

k 

1  With  pressures  below  25  Ib.  there  should  be  no  lift,  and  at  all 
low  pressures,  the  pipes  (steam  especially)  should  be  short,  free  from 
bends,  and  of  full  area  throughout. 

2  The  Table  of  Temperatures  as  it  stands  applies  only  to  a  special 
injector.     For  other  patterns  the  maximum  temperature  at  which 
feed  water  can  be  taken  is  about  10°  lower. 


288 


Appendix    No.  5. 


TABLE  XXXIV. 


SOLUBILITY  OF  ATB  IN  WATER  AT  -760    MILLIMETRE    PRESSURE 
(1  ATMOSPHERE)  AND  VARIOUS  TEMPERATURES  CENTIGRADE. 


o°c 

0-02471 

10°C 

0-01953 

1 

-02406 

11 

•01916 

2 

-02345 

12 

•01882 

3 

•02287 

13 

•01851 

4 

•02237 

14 

•01822 

5 

•02179 

15 

•01795 

6 

•02128 

16 

•01771 

7 

•02080 

17 

•01750 

8 

•02034 

18 

•01732 

9 

•01992 

19 

•01717 

Temp.  F.  =  Temp.  C.  x  f  +32 


TABLE  XXXV. 

TENSION  IN  MILLIMETRES  OF  MERCURY  OF  WATER  VAPOUR  BETWEEN 
-5°  AND  +  35°  C.  OR  23°  TO  95°  F. 


-5 

3-131 

5° 

6-534 

15° 

12-669 

25° 

23-550 

-4 

3«387 

6 

6-998 

16 

13-536 

26 

24-998 

-3 

3*664 

7 

7-492 

17 

14-241 

27 

26-505 

-2 

3-955 

8 

8-017 

18 

15-357 

28 

28-101 

-1 

4-267 

9 

8-574 

19 

16-346 

29 

29-782 

0 

4-600 

10 

9-165 

20 

17-391 

30 

31-548 

1 

4-940 

11 

9-792 

21 

18-495 

31 

33-405 

2 

5-302 

12 

10-457 

22 

19-659 

32 

35-359 

3 

5-687 

13 

11-162 

23 

20-888 

33 

37-410 

4 

6-097 

14 

11-908 

24   22-184 

34 

39-565 

! 

289 


u 


WATER  SOFTENING  AND  TREATMENT 


TABLE  XXXVI. 

VOLUME,  SPECIFIC  GRAVITY  AND  TENSION  OF  WATER  VAPOUR  FROM 
0°  C.  TO  180°  C. 


T°C. 

Atmospheres 
Pressure. 

Pressure  kilos, 
per  Cm2 

Volume  of 
1  Kilo,  of 
Vapour  M3 

Weight  of 
lM3of 
Vapour. 

0° 

_i_ 

0-006 

205-222 

0-005 

18 

-1- 

0-021 

66-145 

0-015 

33 

J- 

0-051 

27-852 

0-036 

46 

To 

0-103 

14-516 

0-069 

60 

i 

0-206 

7-583 

0-032 

65 

i 

0-258 

6-157 

0-162 

82 

| 

0-516 

3-227 

0-310 

92 

0-775 

2-215 

0-451 

100 

i 

1-033 

1-696 

0-591 

112 

ii 

1-549 

1-167 

0-857 

121 

2 

2-066 

0-895 

1-116 

128 

2i 

2-582 

0-729 

1-371 

134 

3 

3-099 

0-617 

1-620 

140 

s* 

3-615 

0-534 

1-866 

144 

4 

4-131 

0-474 

2-108 

148 

4£ 

4-648 

0-426 

2-347 

152 

5 

5-164 

0-387 

2-584 

156 

61 

5-681 

0-355 

2-812 

159 

6 

6-197 

0-328 

3-051 

165 

7 

7-230 

0-285 

3-509 

171 

8 

8-263 

0.252 

3-971 

176 

9 

9-300 

0-227 

4-408 

180 

10 

10-330 

0-206 

4-848 

According  to  Resal  the  specific  weight  and  the  pressure  of 
water  vapour  are  satisfactorily  co-related  by  the  formula 
R=Mpm,  where  R  is  the  specific  weight  of  saturated  water 
vapour  p  =  pressure  in  millimetres  of  mercury,  \ 

M  =  0-001164, 
m  =  0-943. 


290 


APPENDIX 


TABLE  XXXVII. 

OF  THE  RELATIVE  EQUIVALENCE  OF  PRESSURES  IN  MILLIMETRES 
(OR  OTHER  UNITS)  OF  WATER  AND  OF  MERCURY. 


Water. 

Mercury. 

Water.     Mercury. 

Water. 

Mercury. 

Water. 

Mercury. 

1 

0-07 

16 

1-18 

35 

2-58 

200 

14-76 

2 

0-15 

17 

1-26 

40 

2-95 

250 

18-45 

3 

0-22 

18 

1-33 

45 

3-32 

300 

22-14 

4 

0-30 

19 

1-40 

50 

3-69 

350 

25-83 

5 

0-37 

20 

1-48 

55 

4-06 

400 

29-52 

6 

0-44 

21 

1*55 

60 

4-43 

450 

33-21 

7 

0-52 

22 

1-62 

65 

4-80 

500 

36-90 

8 

0-59 

23 

1-70 

70 

5-17 

550 

40-59 

9 

0-66 

24          1-77 

75 

5-54 

600 

44-28 

10 

0-74 

25          1-84 

80 

5-90 

650 

47-97 

11 

0-81 

26          1-92 

85 

6-27 

700 

51-66 

12 

0-89 

27          1-98 

90 

6-64 

800 

59-04 

13 

0-96 

28          2-07 

95 

7-01 

900 

66-42 

14 

1-03 

29           2-14 

100 

7-38 

1000 

73-80 

15 

1-12 

30 

2-21 

150 

11-07 

The  specific  weight  of  mercury  is  13-5501  times  that  of  water. 


291 


WATER    SOFTENING   AND    TREATMENT 


TABLE  XXXVIII. 

TEMPERATURE  AND  PRESSURE  OF  STEAM  FOR  EACH  HALF-INCH  OF 

VACUUM. 


Inches 
of 
Vacuum. 
Mercury 
Column. 

Absolute 
Pressure. 
Lb.  per 
square  inch. 

Temperature 
Degrees  F. 

Inches 
of 
Vacuum. 
Mercury 
Column. 

Absolute 
Pressure. 
Lb.  per 
square  inch. 

Temperature  . 
Degrees  F. 

0 

14-697 

212-00 

15 

7-329 

178-96 

i 

14-451 

211-15 

15£ 

7-084 

177-44 

1 

14-206 

210-29 

16 

6-838 

175-87 

11 

13-960 

209-42 

16£ 

6-592 

174-26 

2 

13-715 

208-54 

17 

6-347 

172-59 

2£ 

13-469 

207-64 

HI 

6-101 

170-86 

3 

13-223 

206-73 

18 

5-856 

169-07 

H 

12-978 

205-80 

18£ 

5-610 

167-23 

4 

12-732 

204-86 

19 

5-364 

165-31 

4i 

12-487 

203-91 

19| 

5-119 

163-32 

5 

12-241 

202-94 

20 

4-873 

161-25 

5| 

11-995 

201-95 

201 

4-628 

159-09 

6 

11-750 

200-95 

21 

4-382 

156-83 

6* 

11-504 

199-93 

21£ 

4-136 

154-46 

7 

11-259 

198-89 

22 

3-891 

151-97 

7| 

11-013 

197-83 

221 

3-755 

149-34 

8 

10-767 

196-75 

23 

3-410 

146-55 

8* 

10-522 

195-65 

231 

3-164 

143-59 

9 

10-276 

194-53 

24 

2-918 

140-42 

9J 

10-031 

193-39 

241 

2-673 

137-01 

10 

9-785 

192-23 

25 

2-427 

133-32 

10i 

9-539 

191-03 

25£ 

2-172 

129-31 

11 

9-294 

189-81 

26 

1-926 

124-89 

HJ 

9-048 

188-57 

26| 

1-680 

119-94 

12 

8-803 

187-30 

27 

1-435 

114-34 

12| 

8-557 

186-00 

271 

1-189 

107-84 

13 

8-311 

184-66 

28 

0-944 

100-05 

13i 

8-066 

183-29 

28J 

0-698 

90-24 

14 

7-820 

181-88 

29 

0-453 

76-80 

UJ 

7-575 

180-44 

29| 

0-207 

54-21 

292 


APPENDIX 


PS  02 

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§ 


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CO(Mi—  i 


o  o  o  o 


CO(Mi—  iO 


CO(Mi—  iOC50OI>O 


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9999 


O^M"— i  i— i  i— <oooocsoooooot^i>-?ocoio»o 

(M(N(N^Hr-H^HF-H^HF-<F.HpHr-HOOOOOOO 


o  o  o  o  d  o  o 


0000000 


oooooooo 


o  o  o  o  o  o  o 


(MOOOOOOOOOOOOOO 


293 


WATER    SOFTENING   AND    TREATMENT 


sit  in 

C<10GOOCOC005COrHC005(MCOOCOCOOC<lCO    ^ 

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I       •       •       •...••...•••••....• 

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l>OOOOC5OrHOQCO'*^10lOCOI>0005OrHrl(C<JCO 
,_|^H^HI_l^F_|^HF_|rHrHrHr-l(M(MC<|C<)C<J 

rHOGpco»oco(NpoiGpco»ocococ^rHq5opcpio-*oqrHO 

294 


APPENDIX 


TABLE  XLI. 

SATURATED  STEAM  :    TEMPERATURE  PRESSURE  TABLE. 


Temp. 
F. 

Absolute 
Pressure 
inlb. 
per  sq.  in. 

Temp. 
F. 

Absolute 
Pressure 
inlb. 
per  sq.  in. 

Temp. 
F. 

Absolute 
Pressure 
inlb. 
per  sq.  in. 

60 

•26 

87 

•63 

114 

1-42 

61 

•26 

88 

•65 

115 

1-46 

62 

•27 

89 

•67 

116 

1-50 

63 

•28 

90 

•69 

117 

1-55 

64 

•29 

91 

•71 

118 

1-59 

65 

•30 

92 

•74 

119 

1-64 

66 

•31 

93 

•76 

120 

1-68 

67 

•32 

94 

•78 

121 

1-73 

68 

•33 

95 

•81 

122 

1-78 

69 

•35 

96 

•83 

123 

1-83 

70 

•36 

97 

•86 

124 

1-88 

71 

•37 

98 

•89 

125 

1-93 

72 

•38 

99 

•91 

126 

1-98 

73 

•40 

100 

•94 

127 

2-04 

74 

•41 

101 

•97 

128 

2-10 

75 

•42 

102 

1-00 

129 

1-15 

76 

•44 

103 

1-03 

130 

2-21 

77 

•45 

104 

•06 

131 

2-27 

78 

•47 

105 

•09 

132 

2-33 

79 

•49 

106 

•13 

133 

2-40 

80 

•50 

107 

•16 

134 

2-46 

81 

•52 

108 

•19 

135 

2-52 

82 

•53 

109 

•23 

136 

2-59 

83 

•55 

110 

•27 

137 

2-66 

84 

•57 

111 

•30 

138 

2-73 

85 

•59 

112 

•34 

139 

2-80 

86 

•61 

113 

•38 

140 

2-88 

UNITS,  DEFINITIONS  AND  EQUIVALENTS. 

The  British  Unit  of  Work  is  the  foot  pound  which  represents 
the  work  done  in  raising  one  pound  one  foot  high. 

The  Metric  Unit  of  Work  is  the  kilogrammetre. 

Power  is  the  amount  of  work  performed  in  a  unit  of  time. 

The  Horse-Power  is  the  unit  of  power  used  by  British  engineers 
and  is  equal  to  33,000  foot  pounds  of  work  per  minute. 

The  French  Horse-Power  is  the   equivalent  of    75  kilogram- 
metres  per  second. 

1  British  Horse-Power  =  1-0139  French  Horse-Power. 


Tables  and  Data. 


Pullen.     Scientific  Publishing  Co. 
295 


WATER   SOFTENING   AND    TREATMENT 

Indicated  Horse-Power  (or  pump  horse-power)  is  the  measure 
of  work  done  by  the  steam  in  the  engine  cyinder  (or  water  in  the 
pump  cylinder)  and  is  calculated  by  the  aid  of  the  indicator 
diagram,  the  data  necessary  being  : — the  mean  effective  pressure 
in  the  cylinder,  the  area  and  the  speed  of  the  piston  or  bucket. 
The  method  of  calculation  is  as  follows  : — 

Let  P  =  The  mean  effective  pressure  of  steam  or  water  in 

pounds  on  the  square  inch. 
A  =  Area  of  piston  in  square  inches. 
L  =  Length  of  stroke  in  feet. 
N  =  Number  of  strokes  per  minute,  in  double-acting 

engines  or  pumps  =  re  vs.  x2. 
Then  P    x    A  =  the  total  mean  effective  pressure  on  the  piston 

in  pounds, 
L    x    N  =  the  distance  in  feet  through  which  the  piston 

moves  in  one  minute  (or  piston  speed), 

and  PA  x  LN  =  the    number   of  foot-pounds  of    work    done 
per  minute  which,  divided   by  one  horse- 
power, or  33,000  foot-pounds. 
PAxLN 
33,000 

gives  the  indicated  Horse-Power  developed 
by  the  engine  or  absorbed  by  a  pump  as 
shown  on  the  Indicator  diagram. 

Indicated  Horse-Power  is  the  external  or  useful  work  done  by 
the  engine,  plus  the  power  to  overcome  the  frictional  resistances 
of  the  engine  itself. 

Brake  Horse-Power  represents  the  external  or  useful  work  done 
by  the  engine,  or  the  Indicated  Hor,se-Power  less  the  power 
absorbed  to  drive  the  engine  itself. 

Thermal  Efficiency. — The  thermal  efficiency  of  an  engine  is 
the  ratio  of  the  amount  of  heat  energy  used  in  doing  work,  to 
the  total  amount  of  heat  energy  received  by  the  engine. 

The  Mechanical  Efficiency  of  the  engine  is  the  ratio  of  the 

BHP 

useful  work  to  the  total  work  done  and  equals  - 

IHP. 

"  Heat  is  a  form  of  molecular  energy,  and  it  may  be  converted 
into  mechanical  work  by  means  of  the  change  of  volume  which 
it  produces  in  bodies  acted  upon  by  it." — (Ripper.) 

"  Heat,  given  to  a  substance  and  warming  it,  is  said  to  be 
'  sensible  '  in  the  substance.  Heat,  given  to  a  substance  and 
not  warming  it,  is  said  to  become  latent." — (Sir  W.  Thomson.) 

"  Latent  Heat,  is  the  quantity  of  heat  which  must  be  com- 
municated to  a  body  in  a  given  state,  in  order  to  convert  it  into 
another  state  without  changing  its  temperature." — (Maxwell, 
"  Theory  of  Heat:') 

296 


APPENDIX 

Units  of  Heat.— The  British  Thermal  Unit  (B.Th.U.)  is  the 
standard  unit  adopted  in  this  country,  and  is  the  heat  required 
to  raise  one  pound  of  water  through  one  degree  Fahrenheit, 
measured  by  some  at  the  standard  temperature  of  60°  F.  but 
Rankine  says  at  or  near  39-1°  F.  =4°C.  or  the  temperature  of 
maximum  density. 

The  mechanical  equivalent  of  the  B.Th.U.,  as  determined  by 
Rowlands,  after  Joule,  is  778  foot  pounds  or  units  of  work,  at 
60°  F. 

The  Metric  Thermal  Unit  is  the  Calorie  and  represents  the  heat 
required  to  raise  one  kilogram  of  water  one  degree  Celsius  or 
Centigrade. 

1  B.Th.U.  =0-252  Calorie. 
1  Calorie  =  3-968  B.Th.U. 
1  Calorie  =  3087  foot  pounds, 

Specific  Heat,  or  capacity  for  heat,  is  the  ratio  of  the  quantity 
of  heat  required  to  raise  one  pound  weight  of  a  given  substance 
through  one  degree  Fahrenheit,  water,  at  the  standard  tem- 
perature of  60°  F.,  being  the  standard  of  comparison. 

TABLE  OF  SPECIFIC  HEATS. 

Constant      Constant 
Pressure       Volume. 

Water  at  60°  F.  =  1-000.  Steam  at  212°  F.  =  0-480  =  0-346. 

Iceat32°F.        =0-504.  Air     ...       =0-217=0-168. 

Iron,  cast.      .     =0-130.  Hydrogen      .         =  3'410  =  2'410. 

Iron,  wrought     =0-113.  Oxygen   .      .         =0-217  =0-155. 

Steel.      .      .     =0-116.  Nitrogen.      .         =0-244=0-173. 
Copper      .      .     =  0-095. 

Temperature. — "  The  temperature  of  a  body  is  its  thermal 
state  considered  with  reference  to  its  power  of  communicating 
heat  to  other  bodies."  (Maxwell.)  Temperature  determines  the 
intensity  of  heat  in  bodies. 

First  Law  of  Thermodynamics. — "  Heat  and  Mechanical  energy 
are  mutually  convertible,  and  heat  requires  for  its  production 
and  produces  by  its  disappearance,  a  definite  number  of  units 
of  work  for  each  thermal  unit." 

Second  Law  of  Thermodynamics. — "  Heat   cannot  pass   from 
a  cold  body  to  a  hot  one  by  a  purely  self-acting  process."- 
(Clausius.) 

The  operation  of  this  law  is  shown  by  the  action  of  the  steam 
in  the  cylinder.  The  steam  at  admission  is  hotter  than  the 
metals  and  gives  up  heat  to  equalize  the  temperatures,  at 
exhaust  the  metals  are  hotter  than  the  steam  and  return  heat 
to  it. 

Evaporation  represents  the  total  weight  of  water  evaporated 
into  steam  at  any  given  pressure,  divided  by  the  net  weight  of 

297 


WATER  SOFTENING  AND  TREATMENT 

dry  fuel  required  to  do  the  work  and  is  expressed  :  —  x  Ib.  steam 
per  Ib.  fuel. 

Equivalent  evaporation  from  and  at  212°  F.  —  For  purposes  of 
comparison,  evaporation  results  in  trials  of  boilers  are  reduced 
to  one  common  standard,  which  is  the  number  of  pounds  of 
water  which  the  same  expenditure  of  heat-units  would  evaporate 
into  steam  at  212°  F.,  from  water  at  212°  F.  The  amount  of 
heat-units  required  to  evaporate  one  pound  of  water  at  212°  F. 
into  steam  at  212°  F.,  is  966  B.Th.U.  The  total  heat  of  evapora- 
tion at  a  given  pressure  is  H  —  (the  heat  of  the  feed  —  32),  and 
therefore  : 

H—  (temp,  feed—  32) 

886 

equivalent  evaporation  from  and  at  212°  F. 

For  superheated  steam,  add  the  heat  units  required  to  raise 
the  temperature  from  that  normal  to  the  pressure  to  the  tem- 
perature of  superheat,  or  (Ts  —  Ti.)  xO'48. 

Goal  is  composed  of  Carbon,  Hydrogen,  Oxygen,  Nitrogen, 
Sulphur,  Ash  and  Water  in  various  proportions.  M.  Mahler  in 
his  work,  Contributions  a  V  Etudes  des  Combustibles,  gives  the 
following  formula  for  ascertaining  the  heating  value  of  the  fuel  : 
14,500  C  +62,100  H—  5,400  (0  +N)  -heating  value  in  B.Th.U. 

Efficiency  of  the  steam  generating  plant  is  the  ratio  of  the 
heat  units  usefully  employed  in  the  generation  of  steam,  as 
shown  by  the  evaporative  result,  to  the  total  heat  units 
supplied  in  the  fuel  thrown  on  the  furnaces. 

The  heating  value  of  the  coal  having  been  ascertained  in 
B.Th.U.,  is  divided  by  966  B.Th.U.,  and  this  gives  the  number 
of  pounds,  which  the  total  heat  of  the  fuel  would  evaporate  from 
and  at  212°  F. 

Absolute  pressure  is  reckoned  from  Zero  or  Vacuum.  On  the 
vacuum  gauge  this  is  represented  by  30  inches  of  mercury,  or 
14  -7  Ib.  below  atmospheric  pressure. 

Boiler  or  gauge  pressure  is  that  above  the  pressure  of  the 
atmosphere  which  is  14*7  Ib.  on  the  square  inch. 

Absolute  pressure  —  14-7  =  boiler  pressure. 

Boiler  pressure  +14*7  =  absolute  pressure. 


THERMOMETER  SCALES. 

32°  Fahrenheit     =    0°  Centigrade  =   0°  Reaumur. 
212°  „  =100°  „         =80° 

(Degrees  Fahr.  -  32)  x  ;]  =  Degrees  Centigrade. 
(Degrees  Fahr.  —  32)  x  %  =  Degrees    Reaumur. 
(Degrees  Centig.  x?)  +32  =  Degrees  Fahr. 
(Degrees  Reaum.  x£)  +32  =  Degrees  Fahr. 
298 


APPENDIX 


"  ECONOMIZERS." 

To  ascertain  the  gain  effected  by  the  use  of  "  economizers," 
i.e.,  feed-water-heaters,  wherein  the  increase  in  temperature  is 
obtained  from  the  waste  gases,  after  leaving  the  boiler ;  or  from 
exhaust  steam  ;  the  following  rule  will  serve  : — 


100  x 


Temperature  of  feed 

leaving  the 
"  economizers  " 


Total  heat  of  steam  at  )       f  Temperature  of  feed 
boiler  pressure  reckoned  >  —  <        entering  the 
w         from  0°  Fahr.          )       L     "  economizers 


(  Temperature  of  feed^ 
entering  the 

6^ed|  =  gain  per  cent, 
effected. 


PROPERTIES  OF  SATURATED  STEAM. 

Rankine  gives  the  relation  between  temperature  and  pressure 
of  dry  saturated  steam  with  great  accuracy,  as  follows  : — 

B       C 
log  p  =  A  -  —  -  — 

where  p  represents  the  absolute  pressure  in  pounds  per  square 
inch, 

A  =  6-1007 

log  B  =  3-43642 

log  0  =  5-59873 

T  =  absolute  temperature  on  the  Fahrenheit  scale,  or  £+461  "2. 
If  T  be  the  Centigrade  scale, 
then  A  =  6-1007 

log  B  =  3-1812 
log  0  =  5-0871 

The  following  table  (XLII.)  by  Professor  Peabody  shows  the 
accuracy  of  Rankine's  equation  as  compared  with  Regnault's 
experiments. 

TABLE  XLII. 


Pressure  in  Ib.  per  sq.  in. 

Temperature  F. 

Experiment. 

Rankine's  Equation. 

32 

•089 

•083 

77 

•455 

•452 

122 

1-779 

1-78 

167 

5-579 

5-58 

212 

14-697 

14-7 

302 

69-27 

69-21 

392 

225-56 

225-9 

428 

336-26 

336.3 

299 


WATER    SOFTENING   AND    TREATMENT 

Specific  Heat.  —  Specific  heat  is  the  heat  required  to  raise  1  Ib. 
water  from  freezing  point  to  the  given  temperature.  The  specific 
heat  of  water  is  not  constant.  The  value  of  the  specific  heat 
S  is  given  with  fair  accuracy  by  the  equation 

S  =  t  +  -00002  t2  +  -0000003  t* 
when  t  is  the  temperature  Centigrade. 

Or  S  =  *  -  32  +  -000000103  (t  -  39)  3 

for  the  Fahrenheit  scale. 

The  specific  heat  at  any  temperature  t°  is  -^-  =  l+2at+3(3t2, 

a  t 

where  S=t  +a  t2  +  fit3  =  the  specific  heat  at  the  temperature  t°. 
Or  consider  any  two  temperatures  tL  and  t.2  ;  then  heat  added 
between  these  temperatures  =  S2  —  S1  =  t2  —  1±  +  a  (t2  2  —  tL  2)  +  B 
(£23—  *i2)  and  the  mean  specific  heat 


On  the  Fahrenheit  scale  it  is,  1-00047  +  -000000103 

pa*  +^2  +^-117(0  H)]. 

Reasoning  from  Rowland's  recent  results  on  the  mechanical 
equivalent  of  heat,  Professor  Peabody  has  shown  the  above 
to  be  not  quite  accurate. 

Latent  Heat  is  the  number  of  British  thermal  units  required 
to  convert  1  Ib.  water  into  dry  saturated  steam  without  change 
of  temperature.  Latent  heat  consists  of  two  parts  :  the  ex- 
ternal work  done  during  evaporation  and  the  actual  intrinsic 
heat  possessed  by  the  steam  in  virtue  of  its  conversion  into 
steam,  and  equal  to  latent  heat  minus  the  heat  equivalent  of 
the  external  work  done  by  the  steam  during  evaporation  ;  or, 


where  P  is  the  pressure  per  square  foot  under  which  the  steam 
was  formed  ;  u  the  increase  in  volume  of  water  and  steam  in 
cubic  feet  during  evaporation,  and  J.  Joule's  mechanical  equiva- 
lent of  heat,  which  is  now  taken  as  778  foot  pounds,  or  426-9 
calories. 

Approximate  expression  for  internal  latent  heat  is 

575-4  --79H 

where  t  is  the  temperature  of  evaporation  on  the  Centigrade  scale  ; 
and 

1062-  -79  t 
on  the  Fahrenheit  scale. 

An  empirical  equation  for  latent  heat  L  is 

L  =  1115  —  -7  ton  the  Fahr.  scale. 
or  L  =   607  -  "7  t  on  the  Cent,  scale. 

300 


X^T*XR$* 

V>     O?  THE 

APPENDIX       INIVERBITY 

OF 

Professor  Unwin's  equation  for  the  latefett^JsaSSSH^e  Centi- 
grade scale  is 

T-77Q  894 

(7-503-  log  p)* 

which  is  very  accurate  where  p  is  the  corresponding  pressure  of 
evaporation  in  pounds  per  square  inch. 

Total  Heat. — The  total  heat  H  required  to  raise  the  tempera- 
ture of  1  Ib.  of  [water  from  32  °  Fahr.  to  a  given  temperature, 
and  evaporate  it  at  that  temperature  is  the  sum  of  the  sensible 
heat,  the  internal  latent  heat,  and  the  external  latent  heat : 

TT  Q      ,    T 

or  H  =  1082  +-305* 

when  t  the  temperature  of  evaporation  Fahrenheit  or 

H  =  606-5  +  -305* 
for  t  on  the  Centigrade  scale. 

External  Work. — The  work  done  by  the  steam  during  forma- 
tion, is  called  the  external  latent  heat.  It  is  approximately 
52  +-091 1  thermal  units  or  on  the  Centigrade  scale  30'6  +'091 1 
thermal  units. 

Specific  Volume. — The  specific  volume  or  volume  of  1  Ib.  of  dry 
saturated  steam  at  different  pressures  can  be  calculated  thus — 

^P  _  JL_  L 

dT  ~~Tu      T(v-S) 

where  v  =  specific  volume  of  1  Ib.  steam  and  3  =  volume  of  1  Ib. 
water  =  -016  cubic  feet. 

For  rough  purposes  the  equation  p  u  1'0646  =479  can  be  used, 
when  u  -  v  —  8  and  p  =  pounds  per  square  inch  of  pressure. 

For  a  fuller  treatment  of  these  matters  see  Tables  and  Data 
by  Pullen.  Scientific  Publishing  Co. 


301 


Appendix  No.    6. 

ELECTRICAL  OIL  SEPARATION 

THE  accompanying  illustration  shows  how  the  problem  of 
oil  separation  from  greasy  water  has  been  electrically  attacked 
by  the  Davis-Perrett  system.  The  air  pump  discharge,  as  hot 


•H  MC  nr  au  «t  o»  u»  OH  w»  «o  «»  «n  vn  in 


,. FIG.  92. 

302 


APPENDIX 

as  it  can  be  obtained,  is  passed  through  a  tank  divided  up  into 
sections,  each  section  being  again  divided  by  iron  plates.  The 
plates  are  then  connected  so  that  the  potential  is  about  40  to 
50  volts  across  each  element.  At  the  Leicester  Corporation 
Tramway  station  there  are  five  plates  in  parallel  and  ten  in 
series  across  a  500  volt  circuit ;  this  plant  will  deal  with  6,000 
gallons  per  hour  and  consumes  about  12  amperes  or  6  units. 
The  plates  last  it  is  said  two  or  three  years  and  when  covered 
with  deposit  they  are  cleaned  by  reversing  the  current  when  the 
deposit  rises  and  can  be  removed.  Grooves  are  cut  into  the 
partitions  dividing  off  the  compartments  and,  the  plates  being 
inserted  in  these  grooves,  are  rigidly  supported.  Iron  rods, 
screwed  their  entire  length,  are  used  for  connecting  the  plates 
together  electrically.  The  whole  apparatus  is  supported  on 
insulators,  and  the  liquid  to  be  treated  is  divided  into  two 
streams  at  one  end  of  the  tanks  ;  it  then  passes  into  the  tanks 
and  through  each  set  of  compartments  in  five  parallel  streams. 
Alternate  plates  are  cut  as  shown  by  the  drawing  so  that  the 
liquid  passes  under  one  plate  and  over  the  next  alternately  and 
circulation  is  so  ensured  over  the  full  surface  of  the  plates.  It 
is  said  that  the  air-pump  discharge  has  a  high  ohmic  resistence 
but  that  the  addition  of  a  small  quantity  of  fresh  water  at  once 
enables  the  liquid  to  conduct  current  and  this  additional  water 
may  of  course  be  added  in  the  form  of  make-up  water.  The 
action  of  the  electric  current  is  to  cause  the  emulsified  oil  to 
coalesce  so  that  it  will  separate  out  by  gravity,  but,  to  save 
space,  it  is  mechanically  filtered.  Sand  (or  in  come  cases  wood 
shavings  tightly  packed  between  perforated  iron  plates,  and 
oak  sawdust)  is  used  for  filtering.  The  iron  plates  are  gradually 
destroyed,  a  brown  oxide  being  formed  and  this,  which  is  a 
hydrated  peroxide,  is  collected  with  the  oil  and  forms  with  it  a 
flocculent  substance.  Whether  the  oxide  is  essential  to  the 
process  is  not  certain,  but  the  result  of  the  process  is  a  clean  and 
bright  water  free  from  oil.  The  space  occupied  varies  from 
100  square  feet  per  1000  gallons  per  hour  up  to  290  square  feet 
for  8,000  gallons  or  approximately  it  would  appear  S  =  100  v/N, 
where  S  =  square  feet  of  space  and  N  =  number  of  thousands  of 
gallons  per  hour.  The  head  room  is  15  to  20  feet. 


303 


INDEX 


Acid,  101,  105 
-  water,  139 
Air,  hygrometry  of,  256 
Air  and  circulating  pumps,  211, 

213 
Air  pump,  149,  194 

-  bucket,  199 

—  combined,  with  circulating 
pump,  211,  213 

-  compound,  213 

-  Davy  Paxman,  204 

-  diagrams,  208 

-  direct  steam-driven,  212 

-  Edwards,  201 

-  ejector,  206 

-  forms  of,  200 

-  Hick  Hargreaves,  207 

-  horizontal,  209 

-  Mirrlees  Watson,  203 

-  rotative,  216 

-  Storey  &  Sons,  203 
—  tail  rod,  210 

-  two-stage  jet  augmentor, 
215 

-  types  of,  201 

-  working  of,  195 

Air,  solubility  of,  in  water,  289 
Alum,  28,  34,  94 
Analysis  of  water,  35,  43 
Angus  Smith,  Dr.,  22,  107,  123 
Apparatus,  commercial,  44,  48 
Archbutt-Deeley  system,  48 
Areas  of  circles,  275 
Atmospheric  evaporator,  260 
—  valve,  190 
Augmentor,  214 


Baker  softener,  63 
Barium  aluminate,  26 


Barium  carbonate,  30 

-  hydrate,  30 
Barometer,  153,  198,  276 
Boiler  cleaners,  119 

-  cleaning,  5,  100 

-  compounds,  96,  98 
French,  97 

-  cooling,  5 

Boiling  point  of  salt  solutions, 

142 

Borings,  deep,  10 
Brackett's,  condenser,  187 
Bruun  Lowener  softener,  68 
Bucket,  air  pump,  199 
Buxton  lime,  22 


Capacity  of  condensers,  160 
Carbonate  of  lime,  13,  19 

-  magnesia,  15,  20 

-  soda,  23 
Carrod  softener,  78 
Caustic  lime,  18,  19  ' 

-  soda,  24,  25,  126 
Centrifugal  pump,  218 
Chalk  lime,  22 

-  water,  10,  123 
Chemicals,  103 
Chemical  oil  separation,  113 
Chevalet  Boby  detartariser,  83 
Circles,  areas  of,  275 
Circulating  pump,  211,  213,  218 

—  Hick  Hargreaves,  219 
-  Pulsomeler  Co.'s,  219 

-  water,  25,  177 
Clarke's  process,  17,  125 
Cleaners,  mechanical  boiler,  119 
Coagulation,  94 

Coefficient  of  contraction,  220 
Cooling  surface,  168 

—  pond,  258 

—  towers,  260 


305 


INDEX 


Cooling  water,  255,  259 
Condenser,  154,  170,  173 

—  atmospheric,  163 

—  Brackett's,  187 

—  calculations,  164 

—  capacity  of,  160 

-  counter- current,  186,  187 

—  ejector,  162 

—  evaporative,  186 

-  Ledward,  175,  184 

-  plant  design,  164 

-  Storey,  176 

-  surface,  189 

-  varieties  of,  160 

-  vertical,  176 

-  Wheeler,  174 

—  Worthington,  173 
Counter- current  condenser,  186, 

187 
Cruse  feed  heater,  235 

D 

Definitions,  295 
Desrumeaux  softener,  70 
Design  of  condensing  plant,  164 
Detartarisers,  83 
Displacement  pump,  219 
Doctor  Angus  Smith,  22 
Dorking  lime,  22 
Doulton  softener,  57 

E 

Economizers,  223,  229 

—  pure  water,  234 
Economy,  6 

—  of  condensing,  7 1 

—  feed  heating,  294 
Edward's  air  pump,  195,  201 
Ejector  condenser,  162 
Electrical  oil  separator,  302 
Equivalence  of  water  and  mer- 
cury, 291 

Equivalents,  29^ 
Evaporator,  atmospheric,  260 
Evaporation  temperature  of  salt 
solutions,  142 

—  factors  of,  293 

—  from  ponds,  259 
Examples  of  condensers,  173 
Exhaust  injector,  284,  286 

—  pipes,  166 


F 

Factors  of  evaporation,  293 
Fan  cooling  tower,  262 
Feed  heating,  223 
Feed  heater,  Paterson,  86 

-  Tray,  242 

-  Weir,  84 

-  heating  in  stages,  237,  244 

-  pumps,    271,    278,    280,    281 

282 

Flow  of  water  in  pipes,  277 
Floury  deposit,  21 
Flue  feed  heater,  223 
Filters,  88,  90,  93 

-  rapid,  93 

-  Reisert,  95 
Filtering  media,  85 
Filtration,  4 

Fromentin  boiler  feeder,  283 
Fully-heated  feed,  235 

G 

Gallon,  standard,  274 
Galvanic  action,  105 
Gases,  solubility  of,  172 
General  design,  164 
Geological  considerations,  8 
Grease,  21,  33,  105 

-  separation,  109,  113 
Guttman's  softener,  60 
Gypsum  water,  123 

H 

Hard  water,  37,  39 
Heat,  149,  151,  295 

—  effect,  4,  29 

—  latent,  150 

—  specific,  149 

-  unit  of,  151 
High  vacuum,  177 
Hotchkiss  cleaner,  119 
Hygrometry  of  air,  256      \ 


Incrustation  in  condensers,  171 

—  pipes,  107 
Injector,  284 

—  capacity  of,  288 

—  combined,  285 

—  exhaust,  284,  286 


306 


INDEX 


Latent  heat,  150,  300 
Law  of  mixed  vapours,  155 
Lead  pipes,  108 
Lime  carbonate,  13,  19 

—  caustic,  18,  19 

—  fat,  22 

—  milk  of,  23 

-  solubility  of,  46 

-  sulphate,  15,  34 

-  unsuitable,  22 

-  water,  23 

Low  pressure  steam,  155 

M 

Magnesia,  24 

—  carbonate  of,  15,  20 

—  sulphate  of,  16 
Mechanical  boiler  cleaners,  119 
Mixed  vapour,  155 

N 
Nozzles,  spray,  267 

O 

Oil  separation,  109,  113,  302 
Organic  matter,  33 
Oxalate  of  soda,  27 


Paterson  feed  heater,  86 

-  oil  separator,  114 

-  softener,  79 
Pipes,  exhaust,  166 

-  flow  in,  277 

-  incrustation  in,  107 

—  silted,  165 
Pond,  cooling,  258 

Position  of  condensing  plant,  217 

Potash,  25,  108 

Pressure  and  head  of  water,  273 

Properties  of  water,  144 

Pure  water,  121 

Pump,  air.     See  Air  Pump. 

Pump,  capacity  of,  280,  283 

—  circulating,  218 

-  direct-acting,  280 

-  feed,  271 

—  flywheel,  282 


Pump,  suction  lift  of,  276 

—  Weir,  278 

—  Worthingtbn,  280 


Reagents,  19,  27 
Recarbonization,  21 
Reisert  filter,  95 
—  softener,  65 
Reservoirs,  258 
Retaining  wall,  91 


Salts  in  water,  13,  142,  144 

-  reactions  of,  19 

—  solutions,  boil,  142 
Sand,  93 

-  filters,  90 

Saturated  steam  table,  295,  299 
Scale  effects,  32,  34 
Settling  ponds,  90 
Softened  water  tests,  50,  63 
Softening  by  soap,  5 

—  systems,  17 
Soap  softening,  5 

-  solutions,  36 
Soda,  23,  27 
Sodium  chloride,  17 
Silicate  of  soda,  27 
Silt  in  pipes,  165 
Smith,  Dr.  Angus,  22 
Solubility  of  air,  289 

-  gases,  41,  140,  172 

-  lime,  46 

-  salts,  142,  144 

Space  occupied  by  apparatus,  75 
Specific  heat,  49 

—  of  water,  241,  300 
Spray  nozzles,  267 
Stage  feed  heating,  237,  244 
Standard  hard  water,  37 
Stanhope  softener,  73 
Steam,  properties  of,  155 

-  table,  295 

-  velocity  of,  167 
Stromeyer  on  softening,  24 
Suction  lift  of  pumps,  276 
Sulphate  of  lime,  15,  34 

-  magnesia,  16 
Surface  condenser,  189 


307 


INDEX 


Temperature,  149 
—  of  evaporation,  142 
Tension  of  water  vapour,  281 
Tests  of  softened  water,  50,  63 
Thermometer  scales,  298 
Towers,  cooling,  260 
Tubular  feed  heaters,  239 
Turbulent  flow,  161 


IT 


Units,  295 

—  of  heat,  151 

—  work,  151 


Vacuum,  high,  177 

—  steam  table,  292 
Vapours,  mixed,  155 

—  pressure,  292 

—  specific  gravity  of,  290 

—  tension  of,  289,  290 

—  volume  of,  290 
Velocity  of  steam,  167 

W 

Walls,  retaining,  91 


Water  acid,  139 

Water  and  mercury,  equivalent 
of,  291 

—  as     affected     by     geological 

chalk,  123 
-  corrections,  8 
Water,  circulating,  177,  257 

—  cooling,  255 

—  effects  of  pure,  4 

—  flow  in  pipes  of,  277 

—  for  condensation,  158 

—  hard,  37,  39 

—  its  sources,  7 

—  pressure  and  head,  273 
— •  properties  of,  17,  144 
— -  pure,  121 

—  river,  9 

—  salts  in,  13 

—  sea,  145 

—  soft,  9 

— •  soluble  powers  of,  41 
— •  specific  gravity  of,  290 

—  —  heat  of,  241 

—  tension  of  vapour,  289,  290 
— •  vapour  density,  290 

—  weight  per  cubic  foot,  144 
Weir  feed  heater,  84 
Wollaston  softener,  76 
Work,  unit  of,  151 


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W.  W.  Practical  Treatise  on  the  Steam-engine  In- 
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BEECH,    F.     Dyeing    of    Cotton    Fabrics.     A    Practical 

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while  to  the  student  it  is  of  value  in  that  the  scientific  principles 
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BECKWITH,  A.     Pottery.     Observations  on  the  Materials 

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lain, Earthenware,  Brick,  Majolica,  and  Encaustic  Tiles.  Second 
Edition.  8vo,  paper 60 

,OCT«a 

BEGTRUP,  J.,  M.E.      The  Slide  Valve  and  its  Functions. 

With  Special  Reference  to  Modern  Practice  in  the  United  States. 
With  numerous  diagrams  and  figures.  8vo,  cloth $2.00 

BERNTHASEN,  A.      A  Text-book  of  Organic  Chemistry. 

Translated  by  George  M'Gowan,  Ph.D.  Fifth  English  Edition, 
revised  and  extended  by  author  and  translator.  Illustrated. 
12mo,  cloth In  Press. 

BERRY,  W.  J.     Differential  Equations  of  the  First  Species. 

12mo,  cloth,  illustrated In  Press. 


6  D.  VAN  NOSTRAND  COMPANY'S 

BERSCH,    J.,    Dr.      Manufacture    of    Mineral    and    Lake 

Pigments.  Containing  directions  for  the  manufacture  of  all 
artificial  artists'  and  painters'  colors,  enamel  colors,  soot  and 
metallic  pigments.  A  text-book  for  Manufacturers,  Merchants, 
Artists  and  Painters.  Translated  from  the  second  revised  edition 
by  Arthur  C.  Wright,  M.A.  8vo,  cloth,  illustrated net,  $5 .00 

BERTIN,  L.  E.      Marine  Boilers:   Their  Construction  and 

Working,  dealing  more  especially  with  Tubulous  Boilers.  Trans- 
lated by  Leslie  S.  Robertson,  Assoc.  M.  Inst.  C.  E.,  M.  I.  Mech.  E., 
M.I.N.A.,  containing  upward  of  250  illustrations.  Preface  by 
Sir  William  White,  K.C.B.,  F.R.S.,  Director  of  Naval  Construc- 
tion to  the  Admiralty,  and  Assistant  Controller  of  the  Navy. 
Second  Edition,  revised  and  enlarged.  8vo,  cloth,  illustrated. 

net,  $5.00 

BIGGS,   C.   H.   W.       First  Principles   of   Electricity   and 

Magnetism.  A  book  for  beginners  in  practical  work,  containing 
a  good  deal  of  useful  information  not  usually  to  be  found  in 
similar  books.  With  numerous  tables  and  343  diagrams  and 
figures.  12mo,  cloth,  illustrated $2 . 00 

BINNS,  C.  F.      Ceramic  Technology.     Being  Some  Aspects 

of  Technical  Science  as  applied  to  Pottery  Manufacture.  8vo, 
cloth net,  $5 . 00 

-  Manual  of  Practical  Potting.      Compiled  by  Experts. 

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BIRCHMORE,  W.  H.,  Dr.      How  to  Use  a  Gas  Analysis. 

12mo,  cloth,  illustrated net ,  $1 . 25 

BLAKE,  W.  H.     Brewer's  Vade  Mecum.     With  Tables  and 

marginal  reference  notes.     8vo,  cloth net,  $4 . 00 


-  W.  P.     Report    upon    the    Precious    Metals.     Being 

Statistical  Notices 
regions  of  the  world, 
tion.     8vo,  cloth. 


ujjuii  tuc  JTICUIUUS  ouciaio.  Joeing 
of  the  Principal  Gold  and  Silver  producing 
d,  represented  at  the  Paris  Universal  Exposi- 

.   $2.00 


BLAKESLEY,  T.  H.     Alternating  Currents  of  Electricity. 

For  the  use  of  Students  and  Engineers.     Third  Edition,  enlarged. 
12mo,  cloth $1 . 50 

BLYTH,  A.  W.,  M.R.C.S.,  F.C.S.  Foods:  Their  Com- 
position and  Analysis.  A  Manual  for  the  use  of  Analytical 
Chemists,  with  an  Introductory  Essay  on  the  History  of  Ad'iltera- 
tions.  With  numerous  tables  and  illustrations.  Fifth  Edition, 
thoroughly  revised,  enlarged  and  rewritten.  8vo,  cloth $7.50 


SCIENTIFIC  PUBLICATIONS.  7 

BLYTH,  A.  W.,  M.R.C.S.,  F.C.S.,  Poisons:  Their  Effects  and 
Detection.  A  Manual  for  the  use  of  Analytical  Chemists  and 
Experts,  with  an  Introductory  Essay  on  the  Growth  of  Modern 
Toxicology.  New  Edition In  Press. 

BODMER,   G.  R.     Hydraulic  Motors  and  Turbines.     For 

the  use  of  Engineers,  Manufacturers  and  Students.  Third  Edi- 
tion, revised  and  enlarged.  With  192  illustrations.  12mo. 
cloth $5.00 

BOILEAU,  J.  T.    A  New  and  Complete  Set  of  Traverse 

Tables,  showing  the  Difference  of  Latitude  and  Departure  of 
every  minute  of  the  Quadrant  and  to  five  places  of  decimals. 
8vo,  cloth $5.00 

BONNEY,     G.    E.      The     Electro-platers1   Handbook.      A 

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60  illustrations.  12mo,  cloth $1 . 20 

BOOTH,  W.  H.  Water  Softening  and  Treatment,  Con- 
densing Plant,  Feed  Pumps,  and  Heaters  for  Steam  Users  and 
Manufacturers.  8vo,  cloth,  illustrated net,  $2.50 

BOURRY,  E.     Treatise  on  Ceramic  Industries.    A  Complete 

Manual  for  Pottery,  Tile  and  Brick  Works.  Translated  from 
the  French  by  Wilton  P.  Rix.  With  323  figures  and  illustrations. 
8vo,  cloth,  illustrated net,  $8.50 

BOW,  R.  H.  A  Treatise  on  Bracing.  With  its  applica- 
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trations. 8vo,  cloth $1 . 50 

BOWIE,   AUG.   J.,   Jr.,   M.E.      A    Practical    Treatise   on 

Hydraulic  Mining  in  California.  With  Description  of  the  Use 
and  Construction  of  Ditches,  Flumes,  Wrought-iron  Pipes  and 
Dams;  Flow  of  Water  on  Heavy  Grades,  and  its  Applicability, 
under  High  Pressure,  to  Mining.  Ninth  Edition.  Small  quarto, 
cloth.  Illustrated $5 . 00 

BOWKER,   Wm.   R.      Dynamo,   Motor    and    Switchboard 

Circuits.  For  Electrical  Engineers.  A  practical  book,  dealing 
with  the  subject  of  Direct,  Alternating,  and  Polyphase  Currents. 
With  over  100  diagrams  and  engravings.  8vo,  cloth.  .  net,  $2.25 

BOWSER,    E.    A.,    Prof.     An    Elementary    Treatise    on 

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12mo,  cloth net,  $1 .75 


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BOWSER,  E.  A.,   Prof.     An   Elementary  Treatise   on  the 

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Twenty-first  Edition.  Enlarged  by  640  additional  examples. 
12mo,  cloth net,  $2 . 25 

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numerous  examples.     Fifth  Edition.     12mo,  cloth net,  $2.50 

A  Treatise  on  Roofs  and  Bridges.     With  Numerous 

Exercises,  especially  adapted  for  school  use.  12mo,  cloth. 
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BRASSEY'S   Naval   Annual   for    1905.     Edited   by   T.   A. 

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tions and  tables.  Nineteenth  year  of  publication.  8vo,  cloth, 
illustrated net,  $6.00 

BRAUN,  E.     The  Baker's  Book:    A  Practical  Handbook 

of  the  Baking  Industry  in  all  Countries.  Profusely  illustrated 
with  diagrams,  engravings,  and  full-page  colored  plates.  Trans- 
lated into  English  and  edited  by  Emil  Braun.  Vol.  I.,  8vo, 

cloth,  illustrated,  308  pages .  . $2 . 50 

Vol.  II.  363  pages,  illustrated $2. 50 

British    Standard    Sections.     Issued    by    the    Engineering 

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Engineers,  The  Institution  of  Mechanical  Engineers,  The  Institu- 
tion of  Naval  Architects,  The  Iron  and  Steel  Institute,  and  The 
Institution  of  Electrical  Engineers.  Comprising  9  plates  of 
diagrams,  with  letter-press  and  tables.  Oblong  pamphlet, 
8fX  15 SI  .00 

BROWN,  WM.  N.     The  Art  of  Enamelling  on  Metal.  With 
figures  and  illustrations.     12mo,  cloth,  illustrated net,  $1 .00 

Handbook  on  Japanning  and  Enamelling,  for  Cycles,  , 

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History  of  Dscorative  Art.     With  Designs  and  Illus- 
trations.    12mo,  cloth net,  $1 . 25 


SCIENTIFIC  PUBLICATIONS.  9 

• 
BROWN,    WM.  N.     Principle    and    Practice    of    Dipping, 

Burnishing,  Lacquering  and  Bronzing  Brass  Ware.     12mo,  cloth. 


Workshop  Wrinkles  for  Decorators,  Painters,  Paper- 

Hangers  and  Others.     8vo,  cloth  ....................  net,  $1  .  00 


BUCHANAN,  E.  E.     Tables  of  Squares.     Containing  the 

square  of  every  foot,  inch,  and  sixteenth  of  an  inch,  between  one 
sixteenth  of  an  inch  and  fifty  feet.  For  Engineers  and  Calcu- 
lators. 16mo,  oblong,  cloth  ...........................  $1  .  00 

BULMAN,   H.   F.,  and   REDMAYNE,   R.  S.   A.     Colliery 

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manager,  the  superintendence  and  arrangement  of  labor  and 
wages,  and  the  different  systems  of  working  coal-seams.  With 
engravings,  diagrams,  and  tables.  Second  Edition,  revised  and 
enlarged.  8vo,  cloth,  illustrated  .....................  net,  $6.00 

BURGH,  N.  P.     Modern  Marine  Engineering,  Applied  to 

Paddle  and  Screw  Propulsion.  Consisting  of  36  colored  plates, 
259  practical  woodcut  illustrations  and  403  pages  of  descriptive 
matter.  The  whole  being  an  exposition  of  the  present  practice 
of  James  Watt  &  Co.,  J.  &  G.  Rennie,  R.  Napier  &  Sons,  and 
other  celebrated  firms.  Thick  quarto,  half  morocco  ........  $10  .  00 

BURT,  W.  A.     Key  to  the  Solar  Compass,  and  Surveyor's 

Companion.  Comprising  all  the  rules  necessary  for  use  in  the 
field;  also  description  of  the  Linear  Surveys  and  Public  Land 
System  of  the  United  States,  Notes  on  the  Barometer,  Sugges- 
tions for  an  Outfit  for  a  Survey  of  Four  Months,  etc.  Seventh 
Edition.  Pocket  size,  full  leather  .......................  $2.  50 

BUSKETT,    E.    W.     Fire    Assaying.     i2mo,    cloth,   illus- 

trated .............................................  In  Press. 

CAIN,   W.,   Prof.     Brief   Course   in   the   Calculus.     With 

figures  and  diagrams.     8vo,  cloth,  illustrated  ..........  net,  $1  .75 

--  Theory    of    Steel-concrete    Arches    and    of    Vaulted 

Structures.  New  Edition,  revised  and  enlarged.  16mo,  cloth,  il- 
lustrated. (Van  Xostrand  Science  Series)  ................  $0  .  50 

CAMPIN,    F.     On    the    Construction    of    Iron    Roofs.     A 

Theoretical  and  Practical  Treatise,  with  woodcuts  and  plates  of 
roofs  recently  executed.  8vo,  cloth  .....................  $2.00 


10  D.  VAN  NOSTRAND  COMPANY'S 

CARPENTER,  Prof.  R.  C.,  and  DIEDERICHS,  Prof.  H. 

Internal  Combustion  Motors.     With  figures  and  diagrams.     8vo. 
cloth,  illustrated In  Press t 

CARTER,  E.  T.  Motive  Power  and  Gearing  for  Elec- 
trical Machinery.  A  treatise  on  the  Theory  and  Practice  of  the 
Mechanical  Equipment  of  Power  Stations  for  Electrical  Supply 
and  for  Electric  Traction.  Second  Edition,  revised  in  part  by  G. 
Thomas-Da  vies.  8vo,  cloth,  illustrated $5.00 

CATHCART,   WM.   L.,   Prof.     Machine   Design.     Part   I. 

Fastenings.    8vo,  cloth,  illustrated net,  $3 . 00 

Machine  Elements ;    Shrinkage  and  Pressure  Joints. 

With  tables  and  diagrams , In  Press. 

Marine-Engine  Design In  Press. 


and  CHAFFEE,  J.  I.     Course  of  Graphic  Statics  Applied 

to  Mechanical  Engineering In  Press 

CHAMBER'S    MATHEMATICAL    TABLES,    consisting    of 

Logarithms  of  Numbers  1  to  108,000,  Trigonometrical,  Nautical 
and  other  Tables.  New  Edition.  8vo,  cloth $1 . 75 

CHARPENTIER,    P.     Timber.     A    Comprehensive    Study 

of  Wood  in  all  its  Aspects,  Commercial  and  Botanical.  Show- 
ing the  Different  Applications  and  Uses  of  Timber  in  Various 
Trades,  etc.  Translated  into  English.  8vo,  cloth,  illus. .  .  net,  $6 . 00 

CHAUVENET,    W.,    Prof.      New    Method    of    Correcting 

Lunar  Distances,  and  Improved  Method  of  Finding  the  Error 
and  Rate  of  a  Chronometer,  by  Equal  Altitudes.  8vo,  cloth.  $2 . 00 

CHILD,    C.    T.     The    How   and   Why   of   Electricity.     A 

Book  of  Information  for  non-technical  readers,  treating  of  the 
Properties  of  Electricity,  and  how  it  is  generated,  handled,  con- 
trolled, measured  and  set  to  work.      Also  explaining  the  opera-  f 
tion  of  Electrical  Apparatus.     8vo,  cloth,  illustrated $1 .00  v 

CHRISTIE,  W.  W.     Boiler-waters,  Scale,  Corrosion,  Foam- 
ing.    8vo,  cloth,  illustrated net,  $3 . 00 

Chimney  Design  and  Theory.     A  Book  for  Engineers 

and  Architects,  with  numerous  half-tone  illustrations  and  plates 
of  famous  chimneys.  Second  Edition,  revised.  8vo,  cloth .  $3 . 00 


SCIENTIFIC  PUBLICATIONS.  11 

CHRISTIE,  W.  W.  Furnace  Draft:  its  Production  by  Me- 
chanical Methods.  A  Handy  Reference  Book,  with  figures  and 
tables.  16mo,  cloth,  illustrated.  (V an Nostrand's  Science  Series). 

$0.50 

CLAPPERTON,   G.     Practical   Paper-making.    A   Manual 

for  Paper-makers  and  Owners  and  Managers  of  Paper  Mills,  to 
which  is  appended  useful  tables,  calculations,  data,  etc.,  with 
illustrations  reproduced  from  micro-photographs.  12mo,  cloth, 
illustrated $2.50 

CLARK,  D.   K.,   C.E.     A  Manual  of  Rules,  Tables  and 

Data  for  Mechanical  Engineers.  Based  on  the  most  recent  inves- 
tigations. Illustrated  with  numerous  diagrams.  1012  pages.  8vo, 
cloth.  Sixth  Edition $5.00 

Fuel :    its  Combustion  and  Economy ;  consisting  of 

abridgments  of  Treatise  on  the  Combustion  of  Coal.  By  C.  W. 
Williams,  and  the  Economy  of  Fuel,  by  T.  S.  Prideaux.  With 
extensive  additions  in  recent  practice  in  the  Combustion  and 
Economy  of  Fuel,  Coal,  Coke,  Wood,  Peat,  Petroleum,  etc. 
Fourth  Edition.  12mo,  cloth $1 . 50 

The   Mechanical   Engineer's   Pocket-book   of    Tables, 

Formulae,  Rules  and  Data.  A  Handy  Book  of  Reference  for 
Daily  Use  in  Engineering  Practice.  16mo,  morocco.  Fifth 
Edition,  carefully  revised  throughout $3 . 00 

Tramways :  Their  Construction  and  Working.  Em- 
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the  various  modes  of  traction,  a  description  of  the  varieties  of 
rolling  stock,  and  ample  details  of  Cost  and  Working  Expenses. 
Second  Edition,  rewritten  and  greatly  enlarged,  with  upwards  of  400 
illustrations.  Thick  8vo,  cloth $89 . 00 

CLARK,  J.  M.  New  System  of  Laying  Out  Railway  Turn- 
outs instantly,  by  inspection  from  tables.  12mo,  cloth. .  .  $1.00 

CLAUSEN-THUE,  W.     The  ABC  Universal  Commercial 

Electric  Telegraphic  Code;  specially  adapted  for  the  use  of 
Financiers,  Merchants,  Ship-owners,  Brokers,  Agents,  etc.  Fourth 

Edition.     8vo,  cloth $5  00 

Fifth  Edition  of  same $7.00 

-The  A  1   Universal  Commercial  Electric  Telegraphic 

Code.  Over  1240  pages  and  nearly  90,000  variations.  8vo, 
cloth $7 . 50 


12  D.  VAN  NOSTRAND  COMPANY'S 

CLEEMANN,   T.   M.     The   Railroad   Engineer's   Practice. 

Being  a  Short  but  Complete  Description  of  the  Duties  of  the 
Young  Engineer  in  Preliminary  and  Location  Surveys  and  in 
Construction.  Fourth  Edition,  revised  and  enlarged.  Illustrated. 
12mo,  cloth $1 . 50 

CLEVENGER,  S.  R.  A  Treatise  on  the  Method  of  Gov- 
ernment Surveying  as  prescribed  by  the  U.  S.  Congress  and  Com- 
missioner of  the  General  Land  Office,  with  complete  Mathemati- 
cal, Astronomical,  and  Practical  Instructions  for  the  use  of  the 
United  States  Surveyors  in  the  field.  16mo,  morocco $2 . 50 

CLOUTH,   F.     Rubber,   Gutta-Percha,   and  Balata.     First 

English   Translation   with   Additions   and   Emendations  .by   the 
Author.      With  numerous  figures,  tables,  diagrams,  and  folding 
8vo,  cloth,  illustrated net,  $5.00 


COFFIN,  J.  H.  C.,  Prof.  Navigation  and  Nautical  Astron- 
omy. Prepared  for  the  use  of  the  U.  S.  Naval  Academy.  New 
Edition.  Revised  by  Commander  Charles  Belknap.  52  woodcut 
illustrations.  12mo,  cloth net,  $3 . 50 

COLE,  R.  S.,  M.A.     A  Treatise  on  Photographic  Optics. 

Being  an  account  of  the  Principles  of  Optics,  so  far  as  they  apply 
to  photography.  12mo,  cloth,  103  illus.  and  folding  plates.  .$2. 50 

COLLINS,  J.  E.  The  Private  Book  of  Useful  Alloys  and 
Memoranda  for  Goldsmiths,  Jewelers,  etc.  18mo,  cloth £0 . 50 

COLLINS,  T.  B.     The  Steam  Turbine,  or  the  New  Engine. 

8vo,  cloth,  illustrated In  Press. 

COOPER,  W.  R.,  M.A.  Primary  Batteries:  Their  Con- 
struction and  Use.  With  numerous  figures  and  diagrams.  8vo, 
cloth,  illustrated net,  $4 . 00 

COPPERTHWAITE,    WM.    C.     Tunnel   Shields,    and   the 

Use  of  Compressed  Air  in  Subaqueous  Works.  With  numerous 
diagrams  and  figures.  4to,  cloth,  illustrated net,  $9 . 00 

COREY,  H.  T.   Water-supply  Engineering.   Fully  illustrated. 

In  Press. 

CORNWALL,  H.  B.,  Prof.     Manual  of  Blow-pipe  Analysis, 

Qualitative  and  Quantitative.  With  a  Complete  System  of 
Determinative  Mineralogy.  8vo,  cloth,  with  many  illustra- 
tions   $2 . 50 


SCIENTIFIC  PUBLICATIONS.  13 

COWELL,  W.  B.  Pure  Air,  Ozone  and  Water.  A  Prac- 
tical Treatise  of  their  Utilization  and  Value  in  Oil,  Grease,  Soap. 
Paint,  Glue  and  other  Industries.  With  tables  and  figures. 
12mo,  cloth,  illustrated net,  $2.00 

CRAIG,   B.  F.     Weights  and  Measures.     An  Account  of 

the  Decimal  System,  with  Tables  of  Conversion  for  Commercial 
and  Scientific  Uses.  Square  32mo,  limp  cloth 50 

CROCKER,  F.  B.,  Prof.     Electric   Lighting.     A  Practical 

Exposition  of  the  Art.  For  use  of  Engineers,  Students,  and 
others  interested  in  the  Installation  or  Operation  of  Electrical 
Plants.  Vol.  I.  The  Generating  Plant.  New  Edition,  thoroughly 

revised  and  rewritten.     8vo,  cloth,  illustrated $3 .00 

Vol.  II.  Distributing  Systems  and  Lamps.  Fifth  Edition.  8vo, 
cloth,  illustrated $3 .00 

• and  WHEELER,  S.  S.    The  Management  of  Electrical 

Machinery.  Being  a  thoroughly  revised  and  rewritten  edition  of 
the  authors'  "Practical  Management  of  Dynamos  and  Motors." 
With  a  special  chapter  by  H.  A.  Foster.  12mo,  cloth,  illustrated. 

n*,$1.00 

CROSSKEY,  L.  R.     Elementary  Perspective:   Arranged  to 

meet  the  requirements  of  Architects  and  Draughtsmen,  and  of 
Art  Students  preparing  for  the  elementary  examination  of  the 
Science  and  Art  Department,  South  Kensington.  With  numer- 
ous full-page  plates  and  diagrams.  8vo,  cloth,  illustrated  .  .  $1 .00 

-  and  THAW,  J.     Advanced  Perspective,  involving  the 

Drawing  of  Objects  when  placed  in  Oblique  Positions,  Shadows 
and  Reflections.  Arranged  to  meet  the  requirements  of  Archi- 
tects, Draughtsmen,  and  Students  preparing  for  the  Perspective 
Examination  of  the  Education  Department.  With  numerous  full- 
page  plates  and  diagrams.  8vo.  cloth,  illustrated $1 . 50 

DA  VIES,    E.    H.     Machinery    for    Metalliferous    Mines. 

A  Practical  Treatise  for  Mining  Engineers,  Metallurgists  and 
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DA  VIES,  D.  C.     A  Treatise  on  Metalliferous  Minerals  and 

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eon.  8vo,  cloth net,  $5.00 

-  Mining  Machinery In  Press. 

DAVISON,  G.  C.,  Lieut.     Water-tube  Boilers In  Press. 


14  D.  VAN  NOSTRAND  COMPANY'S 

DAY,  C.     The  Indicator  and  its  Diagrams.     With  Chap 

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net,  $5.00 

DE  LA  COUX,  H.     The  Industrial  Uses  of  Water.     With 

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French  and  revised  by  Arthur  Morris.  8vo,  cloth net,  $4 . 50 

DENNY,  G.  A.     Deep-level  Mines  of  the  Rand,  and  their 

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DERR,    W.    L.     Block    Signal    Operation.     A    Practical 

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DIETERICH,  K.     Analysis  of  Resins,  Balsams,  and  Gum 

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DIXON,    D.    B.     The    Machinist's   and   Steam   Engineer's  ^ 

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DOBLE,  W.  A.     Power  Plant  Construction  on  the  Pacific 

Coast  ....  .    In  Press. 


SCIENTIFIC  PUBLICATIONS.  15 

DODD,  GEO.  Dictionary  of  Manufactures,  Mining,  Ma- 
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DORR,  B.  F.  The  Surveyor's  Guide  and  Pocket  Table- 
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DRAPER,    C.    H.      An    Elementary   Text-book    of   Light, 

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The  Hydro-Metallurgy  of  Copper.     Being  an  Account 

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ELIOT,    C.   W.,    and   STORER,    F.   H.     A   Compendious. 

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ELLIOT,    G.   H.,   Maj.     European   Light-house    Systems. 

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With  illustrations  and  157  patterns  of  paper  dyed  in  the  pulp, 
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EVERETT,    J.    D.      Elementary    Text-book    of    Physics. 

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SCIENTIFIC  PUBLICATIONS.  17 

FAIRIE,  J.,  F.G.S.  Notes  on  Lead  Ores:  Their  Distribu- 
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FANNING,  J.  T.     A  Practical  Treatise  on  Hydraulic  and 

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FAY,  I.  W.  The  Coal-tar  Colors:  Their  Origin  and  Chem- 
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FISHER,  H.  K.  C.,  and  DARBY,  W.  C.    Students'  Guide 

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FISHER,  W.  C.  The  Potentiometer  and  its  Adjuncts. 
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FLEISCHMANN,  W.     The  Book  of  the  Dairy.     A  Manual 

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FLEMING,  J.  A.,  Prof.  Th?  Alternate-current  Trans- 
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Centenary    of    the    El  ctrical    Current,     1799-1899. 

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FLEMING,  J.  A.,  Prof.  Electric  Lamps  and  Electric  Light- 
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FLEURY,  H.  The  Calculus  Without  Limits  or  Infinitesi- 
mals. Translated  by  C.  O.  Mailloux In  Press 

FOLEY,    N.,    and    PRAY,    THOS.,    Jr.     The    Mechanical 

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FORNEY,  M.  N.     Catechism  of  the  Locomotive.     Second 

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FOSTER,  H.  A.     Electrical  Engineers'  Pocket-book.     With 

the  Collaboration  of  Eminent  Specialists.  A  handbook  of  useful 
data  for  Electricians  and  Electrical  Engineers.  With  innumer- 
able tables,  diagrams,  and  figures.  Third  Edition,  revised 
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FOSTER,    J.    G.,    Gen.,    U.S.A.     Submarine    Blasting    in 

Boston  Harbor,  Massachusetts.  Removal  of  Tower  and  Corwin 
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FOSTER,  J.     Treatise  on  the  Evaporation  of  Saccharine, 

Chemical  and  other  Liquids  by  the  Multiple  System  in  Vacuum 
and  Open  Air.  Third  Edition.  Diagrams  and  large  plates. 
8vo,  cloth .  $7 . 50 


FOX,    WM.,    and    THOMAS,    C.    W.,    M.E.     A    Practical 

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FRANCIS,    J.   B.,    C.E.      Lowell    Hydraulic    Experiments. 

Being  a  selection  from  experiments  on  Hydraulic  Motors  on 
the  Flow  of  Water  over  Weirs,  in  Open  Canals  of  uniform  rect- 
angular section,  and  through  submerged  Orifices  and  diverging 
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enlarged,  with  many  new  experiments,  and  illustrated  with  23 
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SCIENTIFIC  PUBLICATIONS.  19 

FRASER,  R.  H.,  and  CLARK,  C.  H.     Marine  Engineering. 

In  Press. 

FULLER,  G.  W.     Report  on  the  Investigations  into  the 

Purification  of  the  Ohio  River  Water  at  Louisville,  Kentucky, 
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Company.  Published  under  agreement  with  the  Directors. 
3  full-page  plates.  4to,  cloth net,  $10.00 

FURNELL,  J.     Students'  Manual  of  Paints,  Colors,  Oils 

and  Varnishes.     8vo,  cloth,  illustrated net,  $1 .00 

GARCKE,    E.,    and    FELLS,    J.    M.     Factory    Accounts: 

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manufacturers,  with  appendices  on  the  nomenclature  of  machine 
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of  specimen  rulings.  Fifth  Edition,  revised  and  extended.  8vo, 
cloth,  illustrated $3 . 00 

GEIKIE,  J.     Structural  and  Field  Geology,  for  Students  of 

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tone plates.  8vo,  cloth,  illustrated net,  $4.00 

GERBER,  N.     Chemical  and  Physical  Analysis  of  Milk, 
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GERHARD,     WM.     P.       Sanitary    Engineering.       i2mo, 
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GESCHWIND,  L.     Manufacture  of  Alum  and  Sulphates, 

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GIBBS,  W.  E.     Lighting  by  Acetylene,  Generators,  Burners 

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revised.  12mo,  cloth $1 . 50 

GILLMORE,   Q.   A.,   Gen.     Treatise   on  Limes,   Hydraulic 

Cements  and  Mortars.  Papers  on  Practical  Engineering,  United 
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20  D.  VAN  NOSTRAND  COMPANY'S 

GILLMORE,  Q.  A.,  Gen.  Practical  Treatise  on  the  Con- 
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Report   on   Strength   of  the   Building  Stones  in   the 

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GOLDING,   H.  A.     The  Theta-Phi  Diagram.     Practically 

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GOODEVE,   T.   M.     A   Text-book   on   the   Steam-engine. 

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143  illustrations.  12mo,  cloth $2 . 00 

GORE,  G.,  F.R.S.     The  Art  of  Electrolytic  Separation  of 

Metals,  etc.  (Theoretical  and  Practical.)  Illustrated.  8vo, 
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GOULD,  E.  S.  The  Arithmetic  of  the  Steam-engine. 
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GRAY,   J.,   B.Sc.     Electrical   Influence   Machines:     Their 

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Edition,  revised  and  enlarged.  12mo,  cloth,  illus.,  296  pp. .  .  .$2.00 

GREENWOOD,  E.  Classified  Guide  to  Technical  and  Com- 
mercial Books.  Subject  List  of  Principal  British  and  American 
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GRIFFITHS,   A.   B.,   Ph.D.     A  Treatise   on   Manures,   or 

the  Philosophy  of  Manuring.  A  Practical  Handbook  for  the 
Agriculturist,  Manufacturer,  and  Student.  12mo,  cloth.  .  .  $3.00 

Dental    Metallurgy.      A    Manual    for    Students    and 

Dentists.     8vo,  cloth,  illustrated,  208  pp • net,  $3.50 

GROSS,   E.     Hops,   in    their   Botanical,   Agricultural   and 

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and  illustrations.  8vo,  cloth,  illustrated net,  $4 . 50 


SCIENTIFIC  PUBLICATIONS.  21 

GROVER,    F.     Practical    Treatise    on    Modern    Gas    and 

Oil  Engines.     8vo,  cloth,  illustrated net,  $2.0O 

GRUNER,  A.  Power-loom  Weaving  and  Yam  Number- 
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the  weaving  industry.  Illustrated  with  colored  diagrams.  8vo, 
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GURDEN,  R.  L.  Traverse  Tables:  Computed  to  Four- 
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Distance.  For  the  use  of  Surveyors  and  Engineers.  New  Edition. 
Folio,  half  morocco $7 . 50 

GUY,    A.    E.     Experiments    on    the    Flexure    of    Beams, 

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HAEDER,  H.,  C.E.     A  Handbook  on  the  Steam-engine. 

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P.  Powles.  Third  English  Edition,  revised.  8vo,  cloth,  illus- 
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HALL,   C.   H.     Chemistry  of  Paints  and  Paint  Vehicles, 

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HALSEY,   F.   A.     Slide-valve   Gears.     An   Explanation   of 

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Worm    and    Spiral    Gearing.     Revised"  and  Enlarged 

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HAMILTON,    W.    G.     Useful    Information    for    Railway 

Men.     Tenth  Edition,   revised  and  enlarged.     562  pages,  pocket 
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HAMMER,  W.  J.  Radium,  and  Other  Radio-active  Sub- 
stances; Polonium,  Actinium  and  Thorium.  With  a  considera- 
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HANCOCK,  H.  Text-book  of  Mechanics  and  Hydro- 
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HARDY,    E.     Elementary   Principles    of   Graphic    Statics. 

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SCIENTIFIC  PUBLICATIONS.  23 

HART,  J.  W.  Principles  of  Hot-water  Supply.  With 
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24  D.  VAN  NOSTRAND  COMPANY'S 

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HERRMANN,  G.  The  Graphical  Statics  of  Mechanism. 
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HERZFELD,  J.,  Dr.     The  Technical  Testing  of  Yarns  and 

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HORNER,  J.  Engineers'  Turning,  in  Principle  and  Prac- 
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HOUSTON,  E.  J.,  and  KENNELLY,  A.  E.     Algebra  Made 

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HOWORTH,    J.     Art    of   Repairing   and    Riveting    Glass, 

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HUBBARD,  E.  The  Utilization  of  Wood-waste.  A  Com- 
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and  enlarged  edition.  8vo,  cloth,  illustrated,  192  pages.  .  net,  $2. 50 

HUMBER,  W.,  C.E.     A  Handy  Book  for  the  Calculation 

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HURST,  G.  H.,  F.C.S.     Color.     A  Handbook  of  the  Theory 

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—  Dictionary    of    Chemicals    and    Raw    Products    Used 

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SCIENTIFIC  PUBLICATIONS.  27 

HURST,  G.H.,  F.C.S.     Lubricating  Oils;  Fats  and  Greases : 

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HUTCHINSON,  R.  W.,  Jr.     Long  Distance  Electric  Power 

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W.  B.     Patents   and   How   to   Make    Money   out    of 

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The  Works'  Manager's  Handbook   of  Modern  Rules, 

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INGLE,    H.     Manual    of    Agricultural    Chemistry.     Svo, 
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INNES,    C.    H.     Problems   in   Machine    Design.     For   the 

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JANNETTAZ,  E.     A  Guide  to  the  Determination  of  Rocks : 

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JEHL,  F.,  Mem.  A.I.E.E.      The  Manufacture  of  Carbons 

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SCIENTIFIC  PUBLICATIONS.  29 

JOHNSON,  W.  McA.    "The  Metallurgy  of  Nickel."  In  Press. 

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Elements  of  Agricultural  Chemistry  and  Geology.  Seventeenth 
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JONES,  H.  C.  Outlines  of  Electrochemistry.  With 
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JOYNSON,    F.    H.     The    Metals    Used    in     Construction. 

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Designing    and    Construction    of    Machine     Gearing. 

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JUPTNER,  H.  F.  V.     Siderology:    The  Science  of  Iron. 

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KANSAS    CITY    BRIDGE,    THE.     With    an    Account    of 

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Dynamos,  Motors,  Alternators  and  Rotary  Con- 
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KELSEY,    W.    R.      Continuous-current      Dynamos    and 

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KEMPE,   H.   R.     The   Electrical   Engineer's   Pocket-book 

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KENNEDY,  R.     Modern  Engines  and  Power  Generators. 

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SCIENTIFIC  PUBLICATIONS.  31 

KINZBRUNNER,  C.     Alternate  Current  Windings;    Their 

Theory  and  Construction.  A  Handbook  for  Students,  Designers, 
and  all  Practical  Men.  8vo,  cloth,  illustrated net,  $1 .50 

-  Continuous  Current  Armatures;    Their  Winding  and 

Construction.  A  Handbook  for  Students,  Designers,  and  all 
Practical  Men.  8vo,  cloth,  illustrated net,  $1 .50 

KIRKALDY,    W.    G.     Illustrations    of    David    Kirkaldy's 

System  of  Mechanical  Testing,  as  Originated  and  Carried  on  by 
him  during  a  Quarter  of  a  Century.  Comprising  a  Large  Selec- 
tion of  Tabulated  Results,  showing  the  Strength  and  other  Proper- 
ties of  Materials  used  in  Construction,  with  Explanatory  Text 
and  Historical  Sketch.  Numerous  engravings  and  25  lithographed 
plates.  4to,  cloth $10 .00 

KIRKBRIDE,  J.     Engraving  for  Illustration:    Historical 

and  Practical  Notes,  with  illustrations  and  2  plates  by  ink 
photo  process.  8vo,  cloth,  illustrated net,  $1 .50 

KIRKWOOD,   J.   P.     Report  on  the   Filtration   of  River 

Waters  for  the  Supply  of  Cities,  as  practised  in  Europe,  made 
to  the  Board  of  Water  Commissioners  of  the  City  of  St.  Louis. 
Illustrated  by  30  double-page  engravings.  4to,  cloth  ....  $7.50 

KLEIN,   J.    F.      Design    of    a   High-speed   Steam-engine. 

With  notes,  diagrams,  formulas  and  tables.  Second  Edition, 
revised  and  enlarged.  8vo,  cloth,  illustrated net,  $5.00 

KLEINHANS,  F.  B.  Boiler  Construction.  A  Practical  ex- 
planation of  the  best  modern  methods  of  Boiler  Construction, 
from  the  laying  out  of  sheets  to  the  completed  Boiler.  With 
diagrams  and  full-page  engravings.  8vo,  cloth,  illustrated. .  $3 . 00 

KNIGHT,  A.  M.,  Lieut.-Com.  U.S.N.  Modern  Seaman- 
ship. Illustrated  with  136  full-page  plates  and  diagrams.  8vo, 

cloth,  illustrated.     Second  Edition,  revised net,  $6.00 

Half  morocco $7.50 

KNOTT,  C.  G.,  and  MACKAY,  J.  S.     Practical  Mathematics. 

With  numerous  examples,  figures  and  diagrams.  New  Edition. 
8vo,  cloth,  illustrated $2.00 

KOLLER,    T.     The    Utilization    of    Waste    Products.     A 

Treatise  on  the  Rational  Utilization,  Recovery  and  Treatment 
of  Waste  Products  of  all  kinds.  Translated  from  the  German 
second  revised  edition.  With  numerous  diagrams.  8vo,  cloth, 
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32  D.  VAN  NOSTRAND  COMPANY'S 

KOLLER,  T.    Cosmetics.   A  Handbook  of  the  Manufacture, 

Employment  and  Testing  of  all  Cosmetic  Materials  and  Cosmetic 
Specialties.  Translated  from  the  German  by  Chas.  Salter.  8vo. 
cloth net,  $2 . 50 

KRAUCH,    C.,    Dr.     Testing    of    Chemical    Reagents    for 

Purity.  Authorized  translation  of  the  Third  Edition,  by  J.  A. 
Williamson  and  L.  W.  Dupre.  With  additions  and  emendations 
by  the  author.  8vo,  cloth net,  $4 . 50 

LAMBERT,   T.     Lead,  and  its  Compounds.    With  tables, 

diagrams  and  folding  plates.     8vo,  cloth net,  $3 . 50 

Bone    Products     and     Manures.       An     Account     of 

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Animal  Charcoal,  Size,  Gelatine  and  Manures.  With  plans  and 
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LAMBORN,  L.  L.     Cottonseed  Products:  A  Manual  of  the 

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-  Modern  Soaps,  Candles,  and  Glycerin.      A   practical 

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manufacture  of  Soaps  and  Candles,  and  the  recovery  of  Glycerin. 
8vo,  cloth,  illustrated net,  $7 . 50 

LAMPRECHT,    R.     Recovery   Work    after   Pit   Fires.     A 

description  of  the  principal  methods  pursued,  especially  in  fiery 
mines,  and  of  the  various  appliances  employed,  such  as  respira- 
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diagrams.  Translated  from  the  German  by  Charles  Salter.  8vo, 
cloth,  illustrated net,  $4 . 00 

LARRABEE,  C.  S.  Cipher  and  Secret  Letter  and  Tele- 
graphic Code,  with  Hog's  Improvements.  The  most  perfect 
Secret  Code  ever  invented  or  discovered.  Impossible  to  read 
without  the  key.  18mo,  cloth 60 

LASSAR-COHN,  Dr.  An  Introduction  to  Modern  Scien- 
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author's  corrected  proofs  for  the  second  German  edition,  by 
M.  M.  Pattison  Muir,  M.A.  12mo,  cloth,  illustrated $2.00 


SCIENTIFIC  PUBLICATIONS.  33 

LATTA,  M.  N.     Gas  Engineering  Practice.     With  figures, 

diagrams  and  tables.     Mo,  cloth,  illustrated in  Press. 

LEASK,  A.  R.     Breakdowns  at  Sea  and  How  to  Repair 

Them.     With  89  illustrations.     Second  Edition.     8vo,  cloth.  $2.00 

Triple  and  Quadruple  Expansion  Engines  and  Boilers 

and  their  Management.  With  59  illustrations.  Third  Edition, 
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Refrigerating  Machinery:  Its  Principles  and  Man- 
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LECKY,    S.    T.    S.     "Wrinkles"    in   Practical   Navigation. 

With  130  illustrations.  8vo,  cloth.-  Fourteenth  Edition,  revised 
and  enlarged $8 . 00 

LEFEVRE,  L.     Architectural  Pottery :  Bricks,  Tiles,  Pipes, 

Enameled  Terra-Cottas,  Ordinary  and  Incrusted  Quarries,  Stone- 
ware Mosaics,  Faiences  and  Architectural  Stoneware.  With 
tables,  plates  and  950  cuts  and  illustrations.  With  a  preface  by 
M.  J.-C.  Formige.  Translated  from  the  French,  by  K.  H.  Bird, 
M.A.,  and  W.  Moore  Binns.  4to,  cloth,  illustrated net,  $7. 50 

LEHNER,  S.  Ink  Manufacture :  including  Writing,  Copy- 
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lated from  the  fifth  German  edition,  by  Arthur  Morris  and 
Herbert  Robson,  B.Sc.  8vo,  cloth,  illustrated net,  $2.50 

LEMSTROM,  Dr.  Electricity  in  Agriculture  and  Horticul- 
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LEVY,  C.  L.  Electric-light  Primer.  A  simple  and  com- 
prehensive digest  of  all  the  most  important  facts  connected  with 
the  running  of  the  dynamo,  and  electric  lights,  with  precautions 
for  safety.  For  the  use  of  persons  whose  duty  it  is  to  look  after 
the  plant.  8vo,  paper 50 

LIVERMORE,  V.  P.,  and  WILLIAMS,  J.     How  to  Become 

a  Competent  Motorman.  Being  a  Practical  Treatise  on  the 
Proper  Method  of  Operating  a  Street  Railway  Motor  Car;  also 
giving  details  how  to  overcome  certain  defects.  16mo,  cloth, 
illustrated,  132  pages $1 .00 


34  D.  VAN  NOSTRAND  COMPANY'S 

LOBBEN,  P.,  M.E.  Machinists'  and  Draftsmen's  Hand- 
book, containing  Tables,  Rules,  and  Formulas,  with  numerous 
examples,  explaining  the  principles  of  mathematics  and  mechanics, 
as  applied  to  the  mechanical  trades.  Intended  as  a  reference  book 
for  all  interested  in  Mechanical  work.  Illustrated  with  many 
cuts  and  diagrams.  8vo,  cloth $2 . 50 

LOCKE,  A.   G.   and  C.   G.     A  Practical    Treatise  on    the 

Manufacture   of   Sulphuric   Acid.     With   77   constructive   plates,    " 
drawn  to   scale   measurements,   and  other  illustrations.      Royal 
8vo,  cloth.    $10.00 

LOCKERT,  L.     Petroleum  Motor-cars.     i2mo,  cloth,  $1.50 

LCCKWOOD,  T.  D.  Electricity,  Magnetism,  and  Electro- 
telegraphy.  A  Practical  Guide  for  Students,  Operators,  and 
Inspectors.  8vo,  cloth .  Third  Edition $2 . 50 

Electrical  Measurement  and  the  Galvanometer:    its 

Construction  and  Uses.  Second  Edition.  32  illustrations.  12mo, 
cloth $1 . 50 

LODGE,  O.  J.  Elementary  Mechanics,  including  Hydro- 
statics and  Pneumatics.  Revised  Edition.  12mo,  cloth  ...  $1 . 50 

Signalling   Across    Space,   Without    Wires :     being   a 

description  of  the  work  of  Hertz  and  his  successors.  With  numer- 
ous diagrams  and  half-tone  cuts,  and  additional  remarks  con- 
cerning the  application  to  Telegraphy  and  later  developments. 
Third  Edition.  8vo,  cloth,  illustrated net,  $2.00 

LORD,  R.  T.     Decorative  and  Fancy  Fabrics.     A  Valuable 

Book  with  designs  and  illustrations  for  manufacturers  and  de- 
signers of  Carpets,  Damask,  Dress  and  all  Textile  Fabrics.  8vo, 
cloth,  illustrated net,  $3 . 50 

LORING,   A.   E.     A   Handbook   of   the   Electro-magnetic 

Telegraph.     16mo,  cloth,  boards.     New  and  enlarged  edition.  .    .50 

LUCE,  S.  B.  (Com.,  U.  S.  N.).     Text-book  of  Seamanship. 

The  Equipping  and  Handling  of  Vessels  under  Sail  or  Steam. 
For  the  use  of  the  U.  S.  Naval  Academy.  Revised  and  enlarged 
edition,  by  Lieut.  Wm.  S.  Benson.  8vo,  cloth,  illustrated. $10. 00  * 

LUCKE,   C.   E.     Gas  Engine   Design.     With  figures  and 

diagrams.     Second  Edition,  revised.     8vo,  cloth,  illustrated. 

net,  $3.00 

Power,   Cost  and  Plant  Designs   and   Construction. 

In  Press. 


SCIENTIFIC  PUBLICATIONS.  35 

LUCKE,  C.  E.     Power  Plant  Papers.     Form  I.     The  Steam 

Power  Plant.     Pamphlet  (8X  13)  ..............  .....  net,  $1  .50 

LUNGE,   G.,   Ph.D.      Coal-tar  and  Ammonia:    being  the 

third  and  enlarged  edition  of  "A  Treatise  on  the  Distillation  of 
Coal-tar  and  Ammoniacal  Liquor,"  with  numerous  tables,  figures 
and  diagrams.  Thick  8vo,  cloth,  illustrated  .........  net,  $15.00 

-A   Theoretical   and   Practical   Treatise   on   the   Man- 
ufacture of  Sulphuric  Acid  and  Alkali  with  the  Collateral  Branches. 

-  Vol.  I.  Sulphuric  Acid.   In  two  parts,  not  sold  separately. 

Second  Edition,  revised  and  enlarged.   342  illus.   8vo,  cloth  .  .  $15  .  00 

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-  Vol.  III.    Ammonia  Soda,  and  various  other  processes 
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Chlorates,  by  Electrolysis.    8vo,  cloth.   New  Edition,  1896  .  .  $15  .  00- 

--  and  HURTER,  F.      The  Alkali  Maker's  Handbook. 

Tables  and  Analytical  Methods  for  Manufacturers  of  Sulphuric- 
Acid,  Nitric  Acid,  Soda,  Potash  and  Ammonia.  Second  Edition*. 
12mo,  cloth  .........................................  $3  .  OO 

LUPTON,  A.,  PARR,  G.  D.  A.,  and  PERKIN,  H.     Elec- 

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plates.  Second  Edition,  re-vised  and  enlarged.  8vo,  cloth,  illus- 
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LUQUER,  L.  M.,  Ph.D.  (Columbia  Univ.).  Minerals  in 
Rock  Sections.  The  Practical  Method  of  Identifying  Minerals  in 
Rock  Sections  with  the  Microscope.  Especially  arranged  for 
Students  in  Technical  and  Scientific  Schools.  Revised  Edition. 
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MACKIE,    JOHN.     How   to   Make    a   Woolen   Mill   Pay. 

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MACKROW,  C.     The  Naval  Architect's  and  Ship-builder's 

Pocket-book  of  Formulae,  Rules,  and  Tables;   and  Engineers'  and 


Surveyors'    Handy   Book  of   Reference.     Eighth  Edition,  revised 
and  enlarged.     16mo,  limp  leather,  illustrated 


$5.00 


MAGUIRE,   E.,   Capt.,   U.S.A.     The   Attack   and   Defence 

of  Coast  Fortifications.     With  maps  and  numerous  illustrations, 
8vo,  cloth  ...........................................  $2.50 


36  D.  VAN  NOSTRAND  COMPANY'S 

MAGUIRE,    WM.    R.     Domestic    Sanitary    Drainage    and 

Plumbing  Lectures  on  Practical  Sanitation.  332  illustrations. 
8vo $4.00 

MAILLOUX,    C.    0.      Electro-traction    Machinery.      8vo, 

cloth,  illustrated . In  Press. 

MARKS,  E.    C.   R.     Notes  on  the  Construction  of  Cranes 

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-  Notes  on  the  Construction  and  Working  of  Pumps. 

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MARSH,  C.  F.     Reinforced  Concrete.     With  full-page  and 

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MAVER,  W.     American  Telegraphy:   Systems,  Apparatus, 
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MAYER,  A.  M.,  Prof.     Lecture  Notes  on  Physics.     8vo, 
cloth $2.00 

McCULLOCH,  R.  S.,  Prof.     Elementary  Treatise  on  the 

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engines.  8vo,  cloth $3 . 50 

McINTOSH,  J.  G.   Technology  of  Sugar.   A  Practical  Treatise 

on  the  Manufacture  of  Sugar  from  the  Sugar-cane  and  Sugar- 
beet.  With  diagrams  and  tables.  8vo,  cloth,  illustrated .  net,  $4 . 50 

-  Manufacture   of  Varnishes   and    Kindred  Industries. 

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India-rubber  Substitutes.  Second  greatly  enlarged  English  Edi- 

,         tion.     8vo,  cloth,  illustrated net,  $3 . 50 

\        (To  be  complete  in  three  volumes.) 


SCIENTIFIC  PUBLICATIONS.  37 

McNEILL,    B.     McNeill's    Code.     Arranged    to    meet    the 

requirements  of  Mining,  Metallurgical  and  Civil  Engineers,  Direc- 
tors of  Mining,  Smelting  and  other  Companies,  Bankers,  Stock 
and  Share  Brokers,  Solicitors,  Accountants,  Financiers  and 
General  Merchants.  Safety  and  Secrecy.  8vo,  cloth.  ...  $6.00 

McPHERSON,    J.    A.,    A.    M.    Inst.    C.    E.     Waterworks 

Distribution.  A  practical  guide  to  the  laying  out  of  systems  of 
distributing  mains  for  the  supply  of  water  to  cities  and  towns 
With  tables,  folding  plates  and  numerous  full-page  diagrams 
8vo,  cloth,  illustrated $2 . 50 

MERCK,  E.     Chemical  Reagents:  Their  Purity  and  Tests. 

In  Press. 

MERRITT,  WM.  H.     Field  Testing  for  Gold  and  Silver. 

A  Practical  Manual  for  Prospectors  and  Miners.  With  numerous 
half-tone  cuts,  figures  and  tables.  16mo,  limp  leather,  illus- 
trated   $1 . 50 

METAL  TURNING.  By  a  Foreman  Pattern-maker.  Illus- 
trated with  81  engravings.  12mo,  cloth $1 . 50 

MICHELL,  S.  Mine  Drainage:  being  a  Complete  Prac- 
tical Treatise  on  Direct-acting  Underground  Steam  Pumping 
Machinery.  Containing  many  folding  plates,  diagrams  and 
tables.  Second  Edition,  rewritten  and  enlarged.  Thick  8vo, 
cloth,  illustrated $10.00 

MIERZINSKI,  S.,  Dr.  Waterproofing  of  Fabrics.  Trans- 
lated from  the  German  by  Arthur  Morris  and  Herbert  Robson. 
With  diagrams  and  figures.  8vo,  cloth,  illustrated.  .  .  net,  $2.50 

MILLER,  E.  H.  (Columbia  Univ.).     Quantitative  Analysis 

for  Mining  Engineers.    8vo,  cloth net,  $1 . 50 

MINIFIE,    W.     Mechanical    Drawing.     A    Text-book    of 

Geometrical  Drawing  for  the  use  of  Mechanics  and  Schools,  in 
which  the  Definitions  and  Rules  of  Geometry  are  familiarly  ex- 
plained; the  Practical  Problems  are  arranged  from  the  most 
simple  to  the  more  complex,  and  in  their  description  technicalities 
are  avoided  as  much  as  possible.  With  illustrations  for  drawing 
Plans,  Sections,  and  Elevations  of  Railways  and  Machinery;  an 
Introduction  to  Isometrical  Drawing,  and  an  Essay  on  Linear 
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dix on  the  Theory  and  Application  of  Colors.  8vo,  cloth .  .  $4 . 00 


38  D.  VAN  NOSTRAND  COMPANY'S 

MINIFIE,  W.     Geometrical  Drawing.      Abridged  from  the 

octavo  edition,  for  the  use  of  schools.  Illustrated  with  48  steel 
plates.  Ninth  Edition.  12mo,  cloth $2 . 00 

MODERN   METEOROLOGY.     A   Series    of   Six   Lectures, 

delivered  under  the  auspices  of  the  Meteorological  Society  in 
1870.  Illustrated.  12mo,  cloth $1 .50 

MOORE,  E.  C.  S.  New  Tables  for  the  Complete  Solu- 
tion of  Ganguillet  and  Kutter's  Formula  for  the  flow  of  liquids  in 
open  channels,  pipes,  sewers  and  conduits.  In  two  parts.  Part  I, 
arranged  for  1080  inclinations  from  1  over  1  to  1  over  21,120  for 
fifteen  different  values  of  (n).  Part  II,  for  use  with  all  other 
values  of  (n).  With  large  folding  diagram.  8vo,  cloth,  illus- 
trated  net,  $5 . 00 

MOREING,  C.  A.,  and  NEAL,  T.     New  General  and  Mining 

Telegraph  Code.  676  pages,  alphabetically  arranged.  For  the 
use  of  mining  companies,  mining  engineers,  stock  brokers,  financial 
agents,  and  trust  and  finance  companies.  Eighth  Edition.  8vo, 
cloth $5.00 

MOSES,  A.  J.  The  Characters  of  Crystals.  An  Intro- 
duction to  Physical  Crystallography,  containing  321  illustrations 
and  diagrams.  8vo net,  $2 . 00 

and    PARSONS,    C.    L.     Elements    of    Mineralogy, 

Crystallography  and  Blowpipe  Analysis  from  a  Practical  Stand- 
point. Third  Enlarged  Edition.  8vo,  cloth,  336  illustrations, 

net,  $2.50 

MOSS,  S.  A.     Elements  of  Gas  Engine  Design.    Reprint 

of  a  Set  of  Notes  accompanying  a  Course  of  Lectures  delivered 
at  Cornell  University  in  1902.  16mo,  cloth,  illustrated.  (Van 
Nostrand's  Science  Series) $0 . 50 

MOSS,  S.  A.     The  Lay-out  of  Corliss  Valve  Gears.     (Van 

Nostrand's  Science  Series.)     16mo,  cloth,  illustrated $0.50 

MULLIN,  J.  P.,  M.E.  Modern  Moulding  and  Pattern- 
making.  A  Practical  Treatise  upon  Pattern-shop  and  Foundry^ 
Work:  embracing  the  Moulding  of  Pulleys,  Spur  Gears,  Worm 
Gears,  Balance-wheels,  Stationary  Engine  and  Locomotive 
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Propellers,  Pattern-shop  Machinery,  and  the  latest  improve- 
ments in  English  and  American  Cupolas;  together  with  a  large 
collection  of  original  and  carefully  selected  Rules  and  Tables 
for  every-day  use  in  the  Drawing  Office,  Pattern-shop  and  Foundry. 
12mo,  cloth,  illustrated $2 . 50 


SCIENTIFIC  PUBLICATIONS.  39 

MUNRO,  J.,  C.E.,  and  JAMIESON,  A.,  C.E.  A  Pocket- 
book  of  Electrical  Rules  and  Tables  for  the  use  of  Electricians 
and  Engineers.  Fifteenth  Edition,  revised  and  enlarged.  With 
numerous  diagrams.  Pocket  size.  Leather $2 . 50 

MURPHY,  J.  G.,  M.E.     Practical  Mining.     A  Field  Manual 

for  Mining  Engineers.  With  Hints  for  Investors  in  Mining 
Properties.  16mo,  cloth $1 .00 

NAQUET,  A.     Legal  Chemistry.     A  Guide  to  the  Detection 

of  Poisons,  Falsification  of  Writings,  Adulteration  of  Alimentary 
and  Pharmaceutical  Substances,  Analysis  of  Ashes,  and  Exami- 
nation of  Hair,  Coins,  Arms  and  Stains,  as  applied  to  Chemical 
Jurisprudence,  for  the  use  of  Chemists,  Physicians,  Lawyers, 
Pharmacists  and  Experts.  Translated,  with  additions,  including 
a  list  of  books  and  memoirs  on  Toxicology,  etc.,  from  the  French, 
by  J.  P.  Battershall,  Ph.D.,  with  a  Preface  by  C.  F.  Chandler, 
Ph.D.,  M.D.,  LL.D.  12mo,  cloth $2.00 

NASMITH,    J.     The    Student's    Cotton    Spinning.     Third 

Edition,  revised  and  enlarged.  Svo,  cloth,  622  pages,  250  illus- 
trations   $3 . 00 

NEUBURGER,    H.,    and   NOALHAT,   H.     Technology   of 

Petroleum.  The  Oil  Fields  of  the  World:  their  History,  Geog- 
raphy and  Geology.  Annual  Production,  Prospection  and  Develop- 
ment ;  Oil-well  Drilling ; .  Transportation  of  Petroleum  by  Land 
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plates.  Translated  from  the  French,  by  John  Geddes  Mclntosh. 
Svo,  cloth,  illustrated net,  $10.00 

NEWALL,  J.  W.     Plain  Practical  Directions  for  Drawing, 

Sizing  and  Cutting  Bevel-gears,  showing  how  the  Teeth  may 
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them  a  correct  shape  from  end  to  end;  and  showing  how  to  get 
out  all  particulars  for  the  Workshop  without  making  any  Draw- 
ings. Including  a  Full  Set  of  Taoles  of  Reference.  Folding 
plates.  Svo,  cloth $1 . 50 

NEWLANDS,  J.  The  Carpenters'  and  Joiners'  Assistant: 
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and  Strength  of  Materials,  and  the  Mechanical  Principles  of 
Framing,  with  their  application  in  Carpentry,  Joinery  and 
Hand-railing;  also,  a  Complete  Treatise  on  Sines;  and  an  Illus- 
trated Glossary  of  Terms  used  in  Architecture  and  Building. 
Illustrated.  Folio,  half  morocco $15.00 


40  D.  VAN  NOSTRAND  COMPANY'S 

NIPHER,  F.  E.,  A.M.     Theory  of  Magnetic  Measurements, 

with  an  Appendix  on  the  Method  of  Least  Squares.  12mo, 
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NOLL,  AUGUSTUS.     How  to  Wire  Buildings:    A  Manual 

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NUGENT,   E.     Treatise   on   Optics;    or,   Light  and   Sight 

Theoretically  and  Practically  Treated,  with  the  Application  to 
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O'CONNOR,  H.  The  Gas  Engineer's  Pocket-book.  Com- 
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OLSEN,  J.  C.,  Prof.     Text-book  of  Quantitative  Chemical 

Analysis  by  Gravimetric,  Electrolytic,  Volumetric  and  Gasometric 
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OSBORN,  F.  C.     Tables  of  Moments  of  Inertia,  and  Squares 

of  Radii  of  Gyration;  supplemented  by  others  on  the  Ultimate 
and  Safe  Strength  of  Wrought-iron  Columns,  Safe  Strength  of 
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Stresses,  Reactions  and  Bending  Moments  in  Swing  Bridges. 
Fifth  Edition.  12mo,  leather net,  $3. 00 

OUDIN,  M.  A.     Standard  Polyphase  Apparatus  and  Systems. 

With  many  diagrams  and  figures.  Third  Edition,  thoroughly 
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PALAZ,  A.,  Sc.D.     A  Treatise  on  Industrial  Photometry, 

with  special  application  to  Electric  Lighting.     Authorized  trans- 
lation  from   the   French   by  George  W.   Patterson,   Jr.     Second  • 
Edition,  revised.     Svo,  cloth,  illustrated $4 .00 

PAMELY,  C.  Colliery  Manager's  Handbook.  A  Compre- 
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SCIENTIFIC  PUBLICATIONS.  41 

PARR,  G.  D.  A.  Electrical  Engineering  Measuring  Instru- 
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PARRY,  E.  J.,  B.Sc.      The  Chemistry  of  Essential  Oils 

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PARSHALL,    H.    F.,    and  HOBART,    H.    M.      Armature 

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PATERSON,   D.,   F.C.S.      The   Color   Printing   of   Carpet 

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PATTEN,    J.      A   Plan   for   Increasing   the    Humidity    of 

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42  D.  VAN  NOSTRAND  COMPANY'S 

PATTON,    H.     B.      Lecture    Notes    on     Crystallography 

Revised  Edition,  largely  rewritten.  Prepared  for  use  of  the  stu- 
dents at  the  Colorado  School  of  Mines.  With  blank  pages  for 
note-taking.  8vo,  cloth net  $1 . 25 

PAULDING,  C.  P.  Practical  Laws  and  Data  on  the  Con- 
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and  diagrams.     12mo,  cloth,  illustrated net,  $1 .00 

PEIRCE,  B.  System  of  Analytic  Mechanics.  4to, 
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and  other  Uses.  With  numerous  diagrams  and  engravings.  8vo, 
cloth,  illustrated,  287  pages net,  $3.50 

PERRY,  J.      Applied  Mechanics.     A  Treatise  for  the  Use 

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graphical  exercises  illustrating  the  subject.  8vo,  cloth,  650 
pages net,  $2 . 50 

PHILLIPS,     J.       Engineering     Chemistry.      A     Practical 

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Engineering  works,  with  numerous  Analyses,  Examples,  and 
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8vo,  cloth net,  $4 . 50 

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Bullion,  and  the  Chemical  Tests  required    in  the  Processes  of 
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and  engravings.     8vo,  cloth,  illustrated net,  $2 . 50 

PHIN,  J.     Seven  Follies  of  Science.     A  Popular  Account 

of  the  most  famous  scientific  impossibilities  and  the  attempts 
which  have  been  made  to  solve  them;  to  which  is  added  a  small 
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SCIENTIFIC  PUBLICATIONS.  43 

PICKWORTH,  C.  N.  The  Indicator  Handbook.  A  Prac- 
tical Manual  for  Engineers.  Part  I.  The  Indicator:  its  Con- 
struction and  Application.  81  illustrations.  12mo,  cloth.  $1.50 

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Explanation  of  the  Principle  of  Slide-rule  Computation,  together 
with  Numerous  Rules  ana  Practical  Illustrations,  exhibiting  the 
Application  of  the  Instrument  to  the  Eyery-day  Work  of  the 
Engineer — Civil,  Mechanical  and  Electrical.  Seventh  Edition. 
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Plane  Table,  The.  Its  Uses  in  Topographical  Survey- 
ing. From  the  Papers  of  the  United  States  Coast  Survey. 

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PLATTNER'S   Manual    of    Qualitative    and    Quantitative 

Analysis  with  the  Blow-pipe.  Eighth  Edition,  revised.  Translated 
by  Henry  B.  Cornwall,  E.M.,  Ph.D.,  assisted  by  John  H.  Caswell, 
A.M.  From  the  sixth  German  edition,  by  Prof.  Friederich  Kol- 
beck.  With  87  woodcuts.  463  pages.  8vo,  cloth net,  $4 .00 

PLYMPTON,  GEO.   W.,  Prof.      The  Aneroid  Barometer: 

its  Construction  and  Use.  Compiled  from  several  sources. 
Eighth  Edition,  revised  and  enlarged.  16mo,  boards,  illus- 
trated   $0.50 

POCKET   LOGARITHMS,    to    Four   Places   of   Decimals, 

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Tangents  to  Single  Minutes.  To  which  is  added  a  Table  of 
Natural  Sines,  Tangents,  and  Co-tangents.  16mo,  boards.  $0.50 

POPE,  F.  L.     Modern  Practice  of  the  Electric  Telegraph. 

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Fifteenth  Edition,  rewritten  and  enlarged,  and  fully  illustrated.  8vo, 
cloth $1 .50 

POPPLEWELL,  W.  C.     Elementary  Treatise  on  Heat  and 

Heat  Engines.  Specially  adapted  for  engineers  and  students  of 
engineering.  12mo,  cloth,  illustrated $3.00 


44  D.  VAN  NOSTRAND  COMPANY'S 

POPPLEWELL,  W.  C.  Prevention  of  Smoke,  combined 
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Practical   Iron   Founding.     By    the   Author    of   "  Pattern 

Making,"  etc.  Illustrated  with  over  100  engravings.  Third 
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PRAY,  T.,  Jr.     Twenty  Years  with  the  Indicator:    being 

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complex  Formulae.  Illustrated.  8vo,  cloth $2.5^ 

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PREECE,  W.  H.     Electric  Lamps In  Press. 

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Second  Edition,  revised.  8vo,  cloth,  illustrated $3.00 

PREMIER  CODE.     (See  Hawke,  Wm.  H.) 

PRESCOTT,   A.   B.,   Prof.     Organic  Analysis.     A  Manual 

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SCIENTIFIC  PUBLICATIONS.  45 

PRESCOTT,  A.  B.,  Prof.     Outlines  of  Proximate  Organic 

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Determination  of  the  more  'commonly  occurring  Organic  Com- 
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cloth net,  $1 .50 

PRITCHARD,  0.  G.      The  Manufacture   of  Electric-light 

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PULLEN,   W.   W.   F.       Application   of   Graphic  Methods 

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PYNCHON,  T.  R.,  Prof.     Introduction  to  Chemical  Physics, 

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46  D.  VAN  NOSTRAND  COMPANY'S 

RADFORD,  C.  S.,  Lieut.      Handbook  on  Naval  Gunnery. 

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RAM,  G.  S.     The  Incandescent  Lamp  and  its  Manufac- 
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RANDALL,   J.   E.     A   Practical   Treatise    on   the   Incan- 
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RANDALL,    P.    M.     Quartz    Operator's    Handbook.      New 

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RANDAU,  P.     Enamels  and  Enamelling.    An  introduction 

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RANKINE,    W.    J.    M.     Applied    Mechanics.     Comprising 

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Civil    Engineering.      Comprising     Engineering     Sur- 
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SCIENTIFIC  PUBLICATIONS.  47 

RANKINE,  W.  J.  M.  Machinery  and  Millwork.  Compris- 
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RAPHAEL,    F.    C.     Localization    of    Faults    in    Electric 

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RATEAU,  A.     Experimental  Researches  on  the  Flow  of 

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RAUTENSTRAUCH,  Prof.  W.     Syllabus  of  Lectures  and 

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tically Treated.     With  numerous  diagrams  and  figures.     Second 
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RAYNER,  H.     Silk  Throwing   and  Waste  Silk  Spinning. 

With  numerous   diagrams   and   figures.     8vo,   cloth,   illustrated, 

net,  $2.50 

RECIPES    for  the  Color,  Paint,  Varnish,   Oil,  Soap  and 

Drvsaltery  Trades.     Compiled  by  an  Analytical  Chemist.      8vo, 
cloth..  .............................  $3.50 


48  D.  VAN  NOSTRAND  COMPANY'S 

RECIPES  FOR    FLINT  GLASS  MAKING.     Being  Leaves 

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Containing  up-to-date  recipes  and  valuable  information  as  to 
Crystal,  Demi-crystal,  and  Colored  Glass  in  its  many  varieties. 
It  contains  the  recipes  for  cheap  metal  suited  to  pressing,  blowing, 
etc.,  as  well  as  the  most  costly  Crystal  and  Ruby.  British  manu- 
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the  Venetians  to  Hungry  Hill,  Stour bridge,  up  to  the  present 
time.  The  book  also  contains  remarks  as  to  the  result  of  the 
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from  their  own  memoranda  upon  the  originals.  Compiled  by 
a  British  Glass  Master  and  Mixer.  12mo,  cloth net,  $4.50 

REED'S  ENGINEERS'  HANDBOOK  to  the  Local  Marine 

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Key  to  the  Seventeenth  Edition  of  Reed's  Engineers' 

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questions  given  in  the  examination  papers.  By  W.  H.  Thorn. 
8vo,  cloth $3 . 00 

REED.     Useful  Hints  to  Sea-going  Engineers,  and  How  to 

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REINHARDT,  C.  W.     Lettering  for  Draftsmen,  Engineers, 

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REISER,  F.     Hardening  and  Tempering  of  Steel,  in  Theory 

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enlarged  edition,  by  Arthur  Morris  and  Herbert  Robson.  Svo, 
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SCIENTIFIC  PUBLICATIONS.  49 

REISER,  N.     Faults  in  the  Manufacture  of  Woolen  Goods, 

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edition,  by  Arthur  Morris  and  Herbert  Robson.  8vo,  cloth, 
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RICE,  J.  M.,  and  JOHNSON,  W.  W.     On  a  New  Method 

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ne*,$6.00 

ROBERTSON,    L.    S.     Water-tube    Boileri.     Based    on    a 

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ROBINSON,   S.   W.     Practical  Treatise   on  the   Teeth  of 

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ROEBLING,  J.  A.     Long  and  Short  Span  Railway  Bridges. 

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ROLLINS,    W.     Notes    on   X-Light.     With    152    full-page 

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50  D    VAN  NOSTRAND  COMPANY'S 

ROSE,  J.,  M.E.     Key  to  Engines  and  Engine-running.     A 

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SAUNDERS,    C.    H.     Handbook    of    Practical    Mechanics 

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SAUNNIER,  C.     Watchmaker's  Handbook.     A  Workshop 

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SCHELLEN,  H.,  Dr.  Magneto-electric  and  Dynamo- 
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SCIENTIFIC  PUBLICATIONS.  51 

SCHERER,    R.     Casein:    its   Preparation   and   Technical 

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SCHMALL,  C.  N.     First  Course  in  Analytical  Geometry, 

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SCHMEER,  LOUIS.     Flow  of  Water:  A   New  Theory  of 

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SCHUMANN,  F.     A  Manual  of  Heating  and  Ventilation 

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SCHWEIZER,  V.  Distillation  of  Resins,  Resinate    Lakes 

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SCIENCE  SERIES,  The  Van  Nostrand.      (Follows  end  of 

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SCRIBNER,  J.  M.  Engineers'  and  Mechanics'  Com- 
panion. Comprising  United  States  Weights  and  Measures, 
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and  Steam-engine.  Twenty-first  Edition,  revised.  16mo,  full 
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52  D.  VAN  NOSTRAND  COMPANY'S 

SEATON,  A.  E.  A  Manual  of  Marine  Engineering.  Com- 
prising the  Designing,  Construction  and  Working  of  Marine 
Machinery.  With  numerous  tables  and  illustrations  reduced  from 
Working  Drawings.  Fifteenth  Edition,  revised  throughout,  with 
an  additional  chapter  orf  Water-tube  Boilers.  8vo,  cloth .  $6 . 00 

and    ROUNTHWAITE,    H.    M.      A   Pocket-book   of 

Marine  Engineering  Rules  and  Tables.  For  the  use  of  Marine 
Engineers  and  Naval  Architects,  Designers,  Draughtsmen,  Super- 
intendents and  all  engaged  in  the  design  and  construction  of 
Marine  Machinery,  Naval  and  Mercantile.  Seventh  Edition, 
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SEIDELL,    A.     Handbook    of    Solubilities.     i2mo,  cloth. 

in  Press. 

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and  TOWNSEND,  F.     Laboratory  and  Factory  Tests 

in  Electrical  Engineering.  Second  Edition.  8vo,  cloth,  illus- 
trated  net ,  $2 . 50 

SEWALL,   C.   H.     Wireless  Telegraphy.     With    diagrams 

and  engravings.  Second  Edition,  corrected.  8vo,  cloth,  illus- 
trated  net,  $2 . 00 

Lessons    in   Telegraphy.     For   use    as    a    text-book 

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12mo,  cloth $1.00 

SEWELL,    T.     Elements    of    Electrical    Engineering.      A 

First  Year's  Course  for  Students.  Second  Edition,  revised,  with 
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pendix of  Questions  and  Answers.  With  many  diagrams,  tables 
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SEXTON,   A.   H.     Fuel   and   Refractory   Materials.     8vo, 
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Chemistry  of  the  Materials  of  Engineering.    A  Hand- 


book  for   Engineering   Students.      With   tables,    diagrams    and 
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SEYMOUR,  A.     Practical  Lithography.     With  figures  and 

engravings.     8vo,  cloth,  illustrated net,  $2.50 


SCIENTIFIC  PUBLICATIONS.  53 

SHAW,  S.  The  History  of  the  Staffordshire  Potteries,  and 
the  Rise  and  Progress  of  the  Manufacture  of  Pottery  and  Por- 
celain; with  references  to  genuine  specimens,  and  notices  of 
eminent  potters.  A  re-issue  of  the  original  work  published  in 
1829.  8vo,  cloth,  illustrated net,  $3 . 00 

Chemistry    of    the    Several    Natural    and    Artificial 

Heterogeneous  Compounds  used  in  Manufacturing  Porcelain, 
Glass  and  Pottery.  Re-issued  in  its  original  form,  published  in 
1837.  8vo,  cloth net,  $5.00 

t  SHELDON,  S.,  Ph.D.,  and  MASON,  H.,  B.S.  Dynamo- 
electric  Machinery:  its  Construction,  Design  and  Operation, 
Direct-current  Machines.  Fifth  Edition,  revised.  8vo,  cloth,  il- 
lustrated  net,  $2.50 

Alternating-current     Machines:     being    the     second 

volume  of  the  author's  "Dynamo-electric  Machinery :  its  Construc- 
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(Binding  uniform  with  volume  I.)  Fourth  Edition.  8vo,  cloth,, 
illustrated net,  $2.LQ> 


SHIELDS,    J.    E.     Notes    on    Engineering    Construction. 

Embracing  Discussions  of  the  Principles  involved,  and  Descrip- 
tions of  the  Material  employed  in  Tunneling,  Bridging,  Canal  and 
Road  Building,  etc.  12mo,  cloth $1 . 50 

SHOCK,  W.  H.     Steam  Boilers:    their  Design,  Construc- 
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SHREVE,  S    H.     A  Treatise  on  the  Strength  of  Bridges 

and  Roofs.  Comprising  the  determination  of  algebraic  formulas 
for  strains  in  Horizontal,  Inclined  or  Rafter,  Triangular,  Bow- 
string, Lenticular  and  other  Trusses,  from  fixed  and  moving  loads,, 
with  practical  applications  and  examples,  for  the  use  of  Students 
and  Engineers.  87  woodcut  illustrations.  Fourth  Edition.  8vo, 
cloth $3.50 

SHUNK,    W.    F.     The    Field   Engineer.     A   Handy   Book 

of  practice  in  the  Survey,  Location  and  Track-work  of  Railroads, 
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selected,  applicable  to  both  the  Standard  and  Narrow  Gauge, 
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Engineer.  Sixteenth  Edition,  revised  and  enlarged.  With 
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54  D.  VAN  NOSTRAND  COMPANY'S 

SIMMS,  F.  W.     A  Treatise  on  the  Principles  and  Practice 

of  Leveling.  Showing  its  application  to  purposes  of  Railway 
Engineering,  and  the  Construction  of  Roads,  etc.  Revised  and 
corrected,  with  the  addition  of  Mr.  Laws'  Practical  Examples  for 
setting  out  Railway  Curves.  Illustrated.  8  vo,  cloth $2.50 

Practical   Tunneling.     Fourth   Edition,    Revised   and 

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tions. Imperial  8vo,  cloth $8 . 00 

SIMPSON,   G.     The  Naval  Constructor.     A  Vade  Mecum 

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Owners,  Marine  Superintendents,  Engineers  and  Draughtsmen. 
12mo,  morocco,  illustrated,  500  pages net,  $5.00 

SLATER,    J.    W.     Sewage     Treatment,    Purification    and 

Utilization.  A  Practical  Manual  for  the  Use  of  Corporations, 
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SMITH,  F.  E.     Handbook  for  Mechanics.     I2mo,   cloth, 

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SNELL,  A.  T.     Electric  Motive  Power:    The  Transmission 

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Mining  Work.    Second  Edition.    8vo,  cloth,  illustrated. .  net ,  $4 . 00 

SNOW,  W.  G.,  and  NOLAN,  T.     Ventilation  of  Buildings. 

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SCIENTIFIC  PUBLICATIONS.  55 

SOXHLET,  D.  H.  Art  of  Dyeing  and  Staining  Marble, 
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all  sorts  of  Wood.  A  practical  Handbook  for  the  use  of  Joiners, 
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Arthur  Morris  and  Herbert  Robson,  B.Sc.  8vo,  cloth,  170 
pages net,  $2.50 

SPANG,  H.  W.  A  Practical  Treatise  on  Lightning  Pro- 
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SPEYERS,     C.     L.     Text-book     of    Physical     Chemistry. 

8vo,  cloth $2 .25 

STAHL,  A.  W.,  and  WOODS,  A.  T.  Elementary  Mechan- 
ism. A  Text-book  for  Students  of  Mechanical  Engineering. 
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STALEY,  C.,  and  PIERSON,  G.  S.     The  Separate  System 

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STAND  AGE,    H.    C.     Leatherworkers'    Manual:     being   a 

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STEWART,  R.  W.     Text-book  of  Heat.     Illustrated.     8vo, 

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STILES,   A.     Tables   for   Field   Engineers.     Designed   for 

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56  D.  VAN  NOSTRAND  COMPANY'S 

STILLMAN,  P.     Steam-engine  Indicator  and  the  Improved 

Manometer  Steam  and  Vacuum  Gauges;   their  Utility  and  Appli- 
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STODOLA,   Dr.  A.     Steam  Turbines.     With  an  appendix 

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net,  $4 . 50 

STONE,  R.,   Gen'l.     New  Roads  and  Road  Laws  in  the 

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STONEY,  B.  D.     The  Theory  of  Stresses  in  Girders  and 

Similar  Structures.  With  Observations  on  the  Application  of 
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Working  Loads,  Riveting,  Strength  and  Tests  of  Materials. 
777  pages,  143  illus.  and  5  folding-plates.  8vo,  cloth $12.50 

SUPPLING,  E.  R.     Treatise  on  the  Art  of  Glass  Painting. 

Prefaced  with  a  Review  of  Ancient  Glass.  With  engravings  and 
colored  plates.  8vo,  cloth net,  $3 . 50 

SWEET,  S.  H.  Special  Report  on  Coal,  Showing  its  Dis- 
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SWOOPE,  C.  W.  Practical  Lessons  in  Electricity:  Prin- 
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TAILFER,    L.     Practical    Treatise    on    the    Bleaching    of 

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TEMPLETON,  W.      The  Practical  Mechanic's  Workshop 

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SCIENTIFIC  PUBLICATIONS.  57 

THOM,  C.,  and  JONES,  W.  H.     Telegraphic  Connections: 

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of  the  Rules  and  Regulations  concerning  Russian  Oil  Properties. 
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THOMPSON,    E.    P.,    M.E.     How    to    Make    Inventions; 

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Roentgen   Rays   and   Phenomena  of  the  Anode   and 

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THOMPSON,   W.   P.    Handbook   of  Patent  Law  of  All 

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TOCH,  M.     Chemistry  and  Technology  of  Mixed  Paints. 

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58  D.  VAN  NOSTRAND  COMPANY'S 

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SCIENTIFIC  PUBLICATIONS.  59 

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VAN   WAGENEN,   T.   F.     Manual   of  Hydraulic   Mining. 

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VILLON,  A.  M.  Practical  Treatise  on  the  Leather  Industry. 
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60  D.  VAN  NOSTRAND  COMPANY'S 

VINCENT,     C.      Ammonia    and    its    Compounds:     their 

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man. 8vo,  cloth,  illustrated net,  $4 . 00 

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WABNER,    R.     Ventilation    in    Mines.     Translated    from 

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WALKER,    F.,    C.E.      Aerial    Navigation.     A    Practical 

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WALKER,   S.   F.     Electrical  Engineering  in   Our  Homes 

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WALKER,   W.   H.     Screw  Propulsion.     Notes   on   Screw 

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SCIENTIFIC  PUBLICATIONS.  61 

WALLIS  TAYLER,  A.  J.     Bearings  and  Lubrication.     A 

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WANSBROUGH,  W.  D.     The  A  B  C  of  the  Differential 

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WARING,    G.    E.,   Jr.      Sewerage    and    Land    Drainage. 

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Modern    Methods    of   Sewage  Disposals   for   Towns, 

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62  D.  VAN  NOSTRAND  COMPANY'S 

WARING,  G.  E.,  Jr.     How  to  Drain  a  House.     Practical 

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WARREN,    F.    D.     Handbook    on    Reinforced    Concrete. 

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WATT,  A.     Electro-plating  and  Electro-refining  of  Metals: 

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Revised  and  largely  rewritten  by  Arnold  Philip,  B.Sc.  With 
numerous  figures  and  engravings.  8vo,  cloth,  illustrated,  680 
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WEALE,  J.    A  Dictionary  of  Terms  Used  in  Architecture, 

Building,  Engineering,  Mining,  Metullargy,  Archaeology,  the  Fine 
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WEBB,  H.  L.     A  Practical  Guide  to  the  Testing  of  Insu- 
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SCIENTIFIC  PUBLICATIONS.  63 

WEEKES,  R.  W.     The  Design  of  Alternate  Current  Trans- 
formers.    Illustrated.     12mo,  cloth $1 .00 

WEISBACH,    J.     A    Manual    of    Theoretical    Mechanics. 

Xinth  American  edition.  Translated  from  the  fourth  augmented 
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by  Eckley  B.  Coxe,  A.M.,  Mining  Engineer.  1,100  pages  and  902 

woodcut  illustrations.     8vo,  cloth $6 . 00 

Sheep $7.50 

-  and  HERRMANN,  G.     Mechanics  of  Air  Machinery. 

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8vo,  cloth,  illustrated net,  $3 . 75 

WESTON,  E.  B.     Tables  Showing  Loss  of  Head  Due  to 

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WEYMOUTH,  F.  M.     Drum  Armatures  and  Commutators. 

(Theory  and  Practice.)  A  complete  Treatise  on  the  Theory 
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armature  reactions  and  sparking.  8vo,  cloth $3 . 00 

WHEELER,    J.    B.,    Prof.     Art    of   War.      A    Course    of 

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WHIPPLE,  S.,  C.E.     An  Elementary  and  Practical  Treatise 

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WILKINSON,  H.  D.     Submarine  Cable-laying,  Repairing, 

and  Testing.     8vo,  cloth.     New  Edition In  Press. 


64  D.  VAN  NOSTRAND  COMPANY'S 

WILLIAMSON,  R.  S.     On  the  Use  of  the  Barometer  on 

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WILSON,   G.     Inorganic   Chemistry,   with  New  Notation. 

Revised  and  enlarged  by  H.  G.  Madan.  New  edition.  12mo, 
cloth $2 . 00 

WILLSON,    F.    N.     Theoretical    and    Practical    Graphics. 

An  Educational  Course  on  the  Theory  and  Practical  Applications 
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for  students  in  General  Science,  Engraving,  or  Architecture. 
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—  Note-taking,  Dimensioning  and  Lettering.     4to,  Cloth, 

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Third  Angle  Method  of  Making  Working  Drawings. 

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Some    Mathematical    Curves,    and    Their    Graphical 

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WINKLER,  C.,  and  LUNGE,  G.     Handbook  of  Technical 

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with  some  additions  by  George  Lunge,  Ph.D.  8vo,  cloth,  illus- 
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SCIENTIFIC   PUBLICATIONS.  65 

WOODBURY,  D.  V.  Treatise  on  the  Various  Elements 
of  Stability  in  the  Well-proportioned  Arch.  With  numerous 
tables  of  the  Ultimate  and  Actual  Thrust.  8vo,  half  morocco. 
Illustrated $4.00 

WRIGHT,  A.  C.     Analysis  of  Oils  and  Allied  Substances. 

NVO.  cloth,  illustrated,  241  pages net,  $3.50 

-  Simple  Method  for  Testing  Painters'  Materials.     8vo, 
cloth,  160  pages : net,  $2 . 50 

WRIGHT,    T.   W.,    Prof.     (Union    College.)     Elements    of 

Mechanics;  including  Kinematics,  Kinetics  and  Statics.  With  ap- 
plications. Third  Edition,  revised  and  enlarged.  8vo,  cloth.  .  $2 . 50 

-  and  HAYFORD,  J.  F.     Adjustment  of  Observations 

by  the  Method  of  Least  Squares,  with  applications  to  Geodetic 
Work.  Second  Edition,  rewritten.  8vo,  cloth,  illustrated,  net ,  $3 . 00 

YOUNG,  J.  E.     Electrical  Testing  for  Telegraph  Engineers. 

With  Appendices  consisting  of  Tables.     8vo,  cloth,  illus. .  .   $4.00 

YOUNG   SEAMAN'S    MANUAL.     Compiled   from   Various 

Authorities,  and  Illustrated  with  Numerous  Original  and  Select 
Designs,  for  the  Use  of  the  United  States  Training  Ships  and  the 
Marine  Schools.  8vo,  half  roan $3 . 00 

ZEUNER,  A.,  Dr.  Technical  Thermodynamics.  Trans- 
lated from  the  German,  by  Prof.  J.  F.  Klein,  Lehigh  University. 
8vo,  cloth,  illustrated In  Press. 

ZIMMER,  G.  F.  Mechanical  Handling  of  Material.  Be- 
ing a  treatise  on  the  handling  of  material,  such  as  coal,  ore,  tim- 
ber, etc.,  by  automatic  and  semi-automatic  machinery,  together 
with  the  various  accessories  used  in  the  manipulation  of  such 
plant,  also  dealing  fully  with  the  handling,  storing,  and  ware- 
housing of  grain.  With  542  figures,  diagrams,  full-page  and  fold- 
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of  the  Spinning  Process.  A  Text-book  for  Textile,  Trade  and 
higher  Technical  Schools,  as  also  for  self-instruction.  Based  upon 
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Catalogiie  of  the  Van  Nostrand 
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'TPHEY  are  put  up  in  a  uniform,  neat,  and  attractive  form.     i8mot 
boards.      Price  50  cents  per  volume.      The  subjects  are  of  an 
eminently  scientific  character  and  embrace  a  wide  range  of  topics,  and 
are  amply  illustrated  when  the  subject  demands. 

No.  i.  CHIMNEYS  FOR  FURNACES  AND  STEAM  BOILERS.  By 
R.  Armstrong,  C.E.  Third  American  Edition.  Revised  and 
partly  rewritten,  with  an  Appendix  on  "Theory  of  Chimney 
Draught,"  by  F.  E.  Idell,  M.E. 

No.  2.  STEAM-BOILER  EXPLOSIONS.  By  Zerah  Colburn.  New 
Edition,  revised  by  Prof.  R.  H.  Thurston. 

No.  3.  PRACTICAL  DESIGNING  OF  RETAINING-WALLS.  Fourth 
edition,  by  Prof.  W.  Cain. 

No.  4.  PROPORTIONS  OF  PINS  USED  IN  BRIDGES.  By  Charles 
E.  Bender,  C.E.  Second  edition,  with  Appendix. 

No.  5.  VENTILATION  OF  BUILDINGS.  By  Wm.  G.  Snow.  S.B.,  and 
Thos.  Nolan,  A.M. 

No.  6.  ON  THE  DESIGNING  AND  CONSTRUCTION  OF  STORAGE 
Reservoirs.  By  Arthur  Jacob,  B.A.  Third  American  edition, 
revised,  with  additions  by  E.  Sherman  Gould. 

No.  7.  SURCHARGED  AND  DIFFERENT  FORMS  OF  RETAINING- 

walls.     By  James  S.  Tate,  C.E. 

No.  8.  A  TREATISE  ON  THE  COMPOUND  STEAM-ENGINE.  By 
John  Turnbull,  Jr.  2nd  edition,  revised  by  Prof.  S.  W.  Robinson. 

No.  9.  A  TREATISE  ON  FUEL.  By  Arthur  V.  Abbott,  C.E.  Founded 
on  the  original  treatise  of  C.  William  Siemens,  D.C.L.  Third  ed. 

No.  10.  COMPOUND  ENGINES.  Translated  from  the  French  of  A. 
Mallet.  Second  edition,  revised  with  results  of  American  Prac- 
tice, by  Richard  H.  Buel,  C.E. 

No.  ii.  THEORY  OF  ARCHES.     By  Prof.  W.  Allan. 

No.  12.  THEORY  OF  VOUSSOIR  ARCHES.  By  Prof.  Wm.  Cain. 
Third  edition,  revised  and  enlarged. 

No.  13.  GASES  MET  WITH  IN  COAL  MINES.  By  J.  T.  Atkinson. 
Third  edition,  revised  and  enlarged,  to  which  is  added  The  Action 
of  Coal  Dusts  by  Edward  H.  Williams,  Jr. 


D.  VAN  NOSTRAND  CO.'S  SCIENTIFIC  PUBLICATIONS 

No.  14.  FRICTION  OF  AIR  IN  MINES.  By  J.  J.  Atkinson.  Second 
American  edition. 

No.  15.  SKEW  ARCHES.  By  Prof.  E.  W.  Hyde,  C.E.  Illustrated. 
Second  edition. 

No.  16.  GRAPHIC  METHOD  FOR  SOLVING  CERTAIN  QUESTIONS 
in  Arithmetic  or  Algebra.  By  Prof.  G.  L.  Vose.  Second 
edition. 

No.  17.  WATER  AND  WATER-SUPPLY.  By  Prof.  W.  H.  Corfield, 
of  the  University  College,  London.  Second  American  edition. 

No.  18.  SEWERAGE  AND  SEWAGE  PURIFICATION.  By  M.  N. 
Baker,  Associate  Editor  "Engineering  News."  Second  edition, 
revised  and  enlarged. 

No.  19.  STRENGTH  OF  BEAMS  UNDER  TRANSVERSE  LOADS. 
By  Prof.  \V.  Allan,  author  of  "Theory  of  Arches."  Second 
edition,  revised. 

No.  20.  BRIDGE  AND  TUNNEL  CENTRES.  By  John  B.  McMaster, 
C.E.  Second  edition. 

No.  21.  SAFETY  VALVES.     By  Richard  H.  Buel,  C.E.     Third  edition. 

No.  22.  HIGH  MASONRY  DAMS.  By  E.  Sherman  Gould,  M.  Am. 
Soc.  C.  E. 

Ho.  23.  THE  FATIGUE  OF  METALS  UNDER  REPEATED  STRAINS. 
With  various  Tables  of  Results  and  Experiments.  From  the 
German  of  Prof.  Ludwig  Spangenburg,  with  a  Preface  by  S.  H. 
Shreve,  A.M. 

No.  24.  A  PRACTICAL  TREATISE  ON  THE  TEETH  OF  WHEELS. 

By  Prof.  S.  W.  Robinson.     2nd  edition,  revised,  with  additions; 

No.  25.  THEORY  AND  CALCULATION  OF  CANTILEVER  BRIDGES. 
By  R.  M.  Wilcox. 

No.  26.  PRACTICAL  TREATISE  ON  THE  PROPERTIES  OF  CON- 
tinuous  Bridges.  By  Charles  Bender,  C.E. 

No.  27.  BOILER  INCRUSTATION  AND  CORROSION.  By  F.  J. 
Rowan.  New  edition.  Revised  and  partly  rewritten  by  F.  E. 
Idea 

No.  28.  TRANSMISSION  OF  POWER  BY  WIRE  ROPES.  By  Albert 
W.  Stahl,  U.S.N.  Second  edition,  revised. 

No.  29.  STEAM  INJECTORS,  THEIR  THEORY  AND  USE.  Trans- 
lated from  the  French  of  M.  Leon  Pochet. 

No.  30.  MAGNETISM  OF  IRON  VESSELS  AND  TERRESTRIAL 
Magnetism.  By  Prof.  Fairman  Rogers. 


D.  VAN  NOSTRAND  COMPANY'S 

No.  31.  THE    SANITARY   CONDITION  OF   CITY  AND    COUNTRY 

Dwelling-houses.     By  George   E.   Waring,  Jr.     Second   edition, 
revised. 

No.  32.  CABLE-MAKING    FOR    SUSPENSION    BRIDGES.    By    W. 

Hildenbrand,  C.E. 

No.  33.  MECHANICS  OF  VENTILATION.     By  George  W.  Rafter,  C.E. 

Second  edition,  revised. 

No.  34.  FOUNDATIONS.  By  Prof.  Jules  Gaudard,  C.E.  Trans- 
lated from  the  French.  Second  edition. 

No.  35.  THE  ANEROID  BAROMETER:  ITS  CONSTRUCTION  AND 
Use.  Compiled  by  George  W.  Plympton.  Ninth  edition, 
revised  and  enlarged. 

No.  36.  MATTER  AND  MOTION.  By  J.  Clerk  Maxwell,  M.A.  Second 
American  edition. 

No.  37-  GEOGRAPHICAL  SURVEYING:  ITS  USES,  METHODS, 
and  Results.  By  Frank  De  Yeaux  Carpenter,  C.E. 

No.  38.  MAXIMUM  STRESSES  IN  FRAMED  BRIDGES.  By  Prof. 
William  Cain,  A.M.,  C.E.  New  and  revised  edition. 

No.  39.  A  HANDBOOK  OF  THE  ELECTRO-MAGNETIC  TELE- 
graph.  By  A.  E.  Loring.  Fourth  edition,  revised. 

No.  40.  TRANSMISSION  OF  POWER  BY  COMPRESSED  AIR.     By 

Robert  Zahner,  M.E.     New  edition,  in  press. 

No.  41.  STRENGTH  OF  MATERIALS.  By  William  Kent,  C.E., 
Assoc.  Editor  "  Engineering  News."  Second  edition. 

No.  42.  THEORY  OF  STEEL-CONCRETE  ARCHES,  AND  OF 
Vaulted  Structures.  By  Prof.  Wm.  Cain.  Third  edition, 
thoroughly  revised. 

No.  43.  WAVE  AND  VORTEX  MOTION.  By  Dr.  Thomas  Craig, 
of  Johns  Hopkins  University. 

No.  44.  TURBINE  WHEELS.  By  Prof.  W.  P.  Trowbridge,  Columbia 
College.  Second  edition.  Revised. 

No.  45.  THERMO-DYNAMICS.  By  Prof.  H.  T.  Eddy,  University 
of  Cincinnati.  New  edition,  in  press. 

No.  46.  ICE-MAKING  MACHINES.     From  the  French  of  M.  Le  Doux. 
Revised  by  Prof.  J.  E.  Denton,  D.  S.  Jacobus,  and  A.  Riesenberger.    * 
Fifth  edition,  revised. 

No.  47.  LINKAGES:  THE  DIFFERENT  FORMS  AND  USES  OF 
Articulated  Links.  By  J.  D.  C.  De  Roos. 

No.  48.  THEORY  OF  SOLID  AND  BRACED  ELASTIC  ARCHES 
By  William  Cain,  C.E. 

No.  49.  MOTION  OF  A  SOLID  IN  A  FLUID.     By  Thomas  Craig,  Ph.D. 


SCIENTIFIC  PUBLICATIONS. 

No.  50.  DWELLING-HOUSES:  THEIR  SANITARY  CONSTRUC- 
tion  and  Arrangements.  By  Prof.  W.  H.  Corfield. 

No.  51.  THE  TELESCOPE  :  OPTICAL  PRINCIPLES  INVOLVED  IN 
the  Construction  of  Refracting  and  Reflecting  Telescopes,  with 
a  new  chapter  on  the  Evolution  of  the  Modern  Telescope,  and  a 
Bibliography  to  date.  With  diagrams  and  folding  plates.  By 
Thomas  Nolan.  Second  edition,  revised  and  enlarged. 

No.  52.  IMAGINARY  QUANTITIES:  THEIR  GEOMETRICAL  IN- 
terpretation.  Translated  from  the  French  of  M.  Argand  by 
Prof.  A.  S.  Hardy. 

No.  53.  INDUCTION    COILS:     HOW    MADE    AND    HOW    USED. 

Eleventh    American    edition. 

No.  54.  KINEMATICS  OF  MACHINERY.  By  Prof.  Alex.  B.  W. 
Kennedy.  With  an  introduction  by  Prof.  R.  H.  Thurston. 

No.  55.  SEWER  GASES:    THEIR  NATURE  AND  ORIGIN.     By  A. 

de  Varona.     Second  edition,  revised  and  enlarged. 

No.  56.  THE  ACTUAL  LATERAL  PRESSURE  OF  EARTHWORK. 
By  Benj.  Baker,  M.  Inst.,  C.E. 

No.  57.  INCANDESCENT  ELECTRIC  LIGHTING.  A  Practical  De- 
scription of  the  Edison  System.  By  L.  H.  Latimer.  To 
which  is  added  the  Design  and  Operation  of  Incandescent  Sta- 
tions, by  C.  J.  Field ;  and  the  Maximum  Efficiency  of  Incandescent 
Lamps,  by  John  W.  Howell. 

No.  58.  VENTILATION  OF  COAL  MINES.  By  W.  Fairley,  M.E., 
and  Geo.  J.  Andr£. 

No.  59.  RAILROAD  ECONOMICS;    OR,  NOTES  WITH  COMMENTS. 

By  S.  W.  Robinson,  C.E. 

No.  60.  STRENGTH  OF  WROUGHT-IRON  BRIDGE  MEMBERS. 
By  S.  W.  Robinson,  C.E. 

No.  61.  POTABLE    WATER,    AND    METHODS    OF    DETECTING 

Impurities.     By  M.  N.  Baker.    Second  ed.,  revised  and  enlarged. 

No.  62.  THEORY  OF  THE  GAS-ENGINE.  By  Dougald  Clerk.  Third 
edition.  With  additional  matter.  Edited  by  F.  E.  Idell,  M.E. 

No.  63.  HOUSE-DRAINAGE  AND  SANITARY  PLUMBING.  By  W. 
P.  Gerhard.  Tenth  edition. 

No.  64.  ELECTRO-MAGNETS.     By  A.  N.  Mansfield. 

No.  65.  POCKET  LOGARITHMS  TO  FOUR  PLACES  OF  DECIMALS. 

Including  Logarithms  of  Numbers,  etc. 

No.  66.  DYNAMO-ELECTRIC  MACHINERY.  By  S.  P.  Thompson. 
With  an  Introduction  by  F.  L.  Pope.  Third  edition,  revised. 

No.  67.  HYDRAULIC  TABLES  FOR  THE  CALCULATION  OF  THE 
Discharge  through  Sewers,  Pipes,  and  Conduits.  Based  on 
"Kutter's  Formula."  By  P.  J.  Flynn. 


D.  VAN  NOSTRAND  COMPANY'S 

No.  68.  STEAM-HEATING.  By  Robert  Briggs.  Third  edition,  re- 
vised,  with  additions  by  A.  R.  Wolff. 

No.  69.  CHEMICAL    PROBLEMS.     By    Prof.    J.     C.    Foye.     Fourth 

edition,  revised  and  enlarged. 

No.  70.  EXPLOSIVE  MATERIALS.     By  Lieut.  John  P.  Wisser. 

No.  71.  DYNAMIC  ELECTRICITY.  By  John  Hopkinson,  J.  A. 
Shoolbred,  and  R.  E.  Day. 

No.  72.  TOPOGRAPHICAL  SURVEYING.  By  George  J.  Specht. 
Prof.  A.  S.  Hardy,  John  B.  McMaster,  and  H.  F.  Walling.  Third 
edition,  revised. 

No.  73.  SYMBOLIC  ALGEBRA;  OR,  THE  ALGEBRA  OF  ALGE- 

braic  Numbers.     By  Prof.  William  Cain. 

Ns>.  74.  TESTING  MACHINES:  THEIR  HISTORY,  CONSTRUC- 
tion  and  Use.  By  Arthur  V.  Abbott. 

No.  75.  RECENT  PROGRESS  IN  DYNAMO-ELECTRIC  MACHINES. 

Being    a    Supplement    to    "Dynamo-electric    Machinery."      By 
Prof.  Sylvanus  P.  Thompson. 

No.  76.  MODERN    REPRODUCTIVE    GRAPHIC    PROCESSES.     By 

Lieut.  James  S.  Pettit,  U.S.A. 

No.  77.  STADIA  SURVEYING.  The  Theory  of  Stadia  Measure- 
ments. By  Arthur  Winslow.  Sixth  edition. 

No.  78.  THE  STEAM-ENGINE  INDICATOR  AND  ITS  USE.  By 
W.  B.  Le  Van. 

No.  79.  THE  FIGURE  OF  THE  EARTH.     By  Frank  C.  Roberts,  C.E. 

No.  80.  HEALTHY  FOUNDATIONS  FOR  HOUSES.  By  Glenn 
Brown. 

No.  81.  WATER  METERS:   COMPARATIVE  TESTS  OF  ACCURACY, 

Delivery,  etc.     Distinctive   features  of   the   Worthington,    Ken- 
nedy, Siemens,  and  Hesse  meters.     By  Ross  E.  Browne. 

No.  82.  THE  PRESERVATION  OF  TIMBER  BY  THE  USE  OF  ANTI- 

septics.     By  Samuel  Bagster  Boulton,  C.E. 

No.  83.  MECHANICAL  INTEGRATORS.  By  Prof.  Henry  S.  H. 
Shaw,  C.E. 

No.  84.  FLOW  OF  WATER  IN  OPEN  CHANNELS,  PIPES,  CON- 
duits,  Sewers,  etc.  With  Tables.  By  P.  J.  Flynn,  C.E. 

No.  85.  THE  LUMINIFEROUS  AETHER.     By  Prof.  De  Volson  Wood. 

No.  86.  HANDBOOK   OF   MINERALOGY:     DETERMINATION,    DE- 

scription,  and   Classification     f   Minerals   Found    in   the  United 
States.     By  Prof.  J.  C.  Foye.     Fifth  edition,  revised. 


SCIENTIFIC  PUBLICATIONS. 

No.  87.  TREATISE  ON  THE  THEORY  OF  THE  CONSTRUCTION 

of  Helicoidal  Oblique  Arches.     By  John  L.  Culley,  C.E. 

No.  88.  BEAMS  AND  GIRDERS.  Practical  Formulas  for  their  Resist- 
ance. By  P.  H.  Philbrick. 

No.  89.  MODERN  GUN  COTTON:  ITS  MANUFACTURE,  PROP- 
erties,  and  Analyses.  By  Lieut.  John  P.  Wisser,  U.S.A. 

No.  90.  ROTARY   MOTION  AS  APPLIED    TO    THE   GYROSCOPE. 

By  Major  J.  G.  Barnard. 

No.  91.  LEVELING:  BAROMETRIC,  TRIGONOMETRIC,  AND 
Spirit.  By  Prof.  I.  O.  Baker.  Second  edition. 

No.  92.  PETROLEUM:  ITS  PRODUCTION  AND  USE.  By  Boverton 
Redwood,  F.I.C.,  F.C.S. 

No.  93.  RECENT  PRACTICE  IN  THE  SANITARY  DRAINAGE  OF 
Buildings.  With  Memoranda  on  the  Cost  of  Plumbing  Work. 
Second  edition,  revised  and  enlarged.  By  William  Paul  Ger- 
hard, C.E. 

No.  94.  THE  TREATMENT  OF  SEWAGE.  By  Dr.  C.  Meymott 
Tidy. 

No.  95.  PLATE-GIRDER  CONSTRUCTION.  By  Isami  Hiroi,  C.E. 
Fourth  edition,  revised. 

No.  96.  ALTERNATE  CURRENT  MACHINERY.  By  Gisbert  Kapp, 
Assoc.  M.  Inst.,  C.E. 

No.  97.  THE  DISPOSAL  OF  HOUSEHOLD  WASTES.     By  W.  Paul 

Gerhard,  Sanitary  Engineer 

No.  98.  PRACTICAL  DYNAMO-BUILDING  FOR  AMATEURS.  HOW 
to  Wind  for  Any  Output.  By  Frederick  Walker.  Fully  illus- 
trated. Third  edition. 

No.  99.  TRIPLE-EXPANSION  ENGINES  AND  ENGINE  TRIALS. 
By  Prof.  Osborne  Reynolds.  Edited  with  notes,  etc.,  by  F.  E. 
Idell,  M.E. 

No.  100.  HOW  TO  BECOME  AN  ENGINEER;  or,  The  Theoretical 
and  Practical  Training  necessary  in  Fitting  for  the  Duties  of 
the  Civil  Engineer.  By  Prof.  Geo.  W.  Plympton. 

No.  10 1.  THE  SEXTANT,  and  Other  Reflecting  Mathematical  Instru- 
ments. With  Practical  Hints  for  their  Adjustment  and  Use. 
By  F.  R.  Bramard,  U.  S.  Navy. 

No.  102.  THE  GALVANIC  CIRCUIT  INVESTIGATED  MATHE- 
matically.  By  Dr.  G.  S.  Ohm,  Berlin,  1827.  Translated  by 
William  Francis.  With  Preface  and  Notes  by  the  Editor,  Thomas 
D.  Lockwood,  M.I.E.E. 


D.  VAN  NOSTRAND  COMPANY'S 

No.  103.  THE  MICROSCOPICAL  EXAMINATION  OF  POTABLE 
Water.  With  Diagrams.  By  Geo.  W.  Rafter.  Second  edition. 

No.  104.  VAN  NOSTRAND'S  TABLE-BOOK  FOR  CIVIL  AND  ME- 

chanical  Engineers.     Compiled  by  Prof.  Geo.  W.  Plympton. 

No.  105.  DETERMINANTS.  An  Introduction  to  the  Study  of,  with 
Examples  and  Applications.  By  Prof.  G.  A.  Miller. 

No.  106.  COMPRESSED  AIR.  Experiments  upon  the  Transmission  of 
Power  by  Compressed  Air  in  Paris.  (Popp's  System.)  By 
Prof.  A.  B.  W.  Kennedy.  The  Transmission  and  Distribution 
of  Power  from  Central  Stations  by  Compressed  Air.  By  Prof. 
W.  C.  Unwin.  Edited  by  F.  E.  Idell.  Third  edition. 

No.  107.  A    GRAPHICAL    METHOD    FpR    SWING    BRIDGES.      A 

Rational  and  Easy  Graphical  Analysis  of  the  Stresses  in  Ordinary 
Swing  Bridges.  With  an  Introduction  oh  the  General  Theory 
of  Graphical  Statics,  with  Folding  Plates.  By  Benjamin  F. 
La  Rue. 

No.  108.  SLIDE-VALVE  DIAGRAMS.  A  French  Method  for  Con- 
structing Slide-valve  Diagrams.  By  Lloyd  Bankson,  B.S., 
Assistant  Naval  Constructor,  U.  S.  Navy.  8  Folding  Plates. 

No.  109.  THE  MEASUREMENT  OF  ELECTRIC  CURRENTS.  Elec- 
trical Measuring  Instruments.  By  James  Swinburne.  Meters 
for  Electrical  Energy.  By  C.  H.  Wordingham.  Edited,  with 
Preface,  by  T.  Commerford  Martin.  With  Folding  Plate  and 
Numerous  Illustrations. 

No.  no.  TRANSITION  CURVES.  A  Field-book  for  Engineers,  Con- 
taining Rules  and  Tables  for  Laying  out  Transition  Curves.  By 
Walter  G.  Fox,  C.E. 

No.  in.  GAS-LIGHTING  AND  GAS-FITTING.  Specifications  and 
Rules  for  Gas-piping.  Notes  on  the  Advantages  of  Gas  for 
Cooking  and  Heating,  and  Useful  Hints  to  Gas  Consumers.  Third 
edition.  By  Wm.  Paul  Gerhard,  C.E. 

No.  112.  A  PRIMER  ON  THE  CALCULUS,  By  E.  Sherman  Gould, 
M.  Am.  Soc.  C.  E.  Third  edition,  revised  and  enlarged. 

No.  113.  PHYSICAL  PROBLEMS  and  Their  Solution.  By  A.  Bour- 
gougnon,  formerly  Assistant  at  Bellevue  Hospital.  Second  ed. 

No.  114.  MANUAL  OF  THE  SLIDE  RULE.  By  F.  A.  Halsey,  of 
the  "American  Machinist."  Third  edition,  corrected. 

No.  115.  TRAVERSE  TABLE.  Showing  the  Difference  of  Latitude 
and  Departure  for  Distances  Between  1  and  100  and  for  Angles  to 
Quarter  Degrees  Between  1  Degree  and  90  Degrees.  (Reprinted 
from  Seribner's  Pocket  Table  Book.) 


SCIENTIFIC  PUBLICATIONS. 

No.  116.  WORM  AND  SPIRAL  GEARING.  Reprinted  from  "Ameri- 
can Machinist."  By  F.  A.  Halsey.  Second  revised  and  enlarged 
edition. 

No.  117.  PRACTICAL  HYDROSTATICS,  AND  HYDROSTATIC  FOR- 
mulas.  With  Numerous  Illustrative  Figures  and  Numerical 
Examples.  By  E.  Sherman  Gould. 

No.  118.  TREATMENT  OF  SEPTIC  SEWAGE,  with  Diagrams  and 
Figures.  By  Geo.  W.  Rafter. 

No.  119.  LAY-OUT  OF  CORLISS  VALVE  GEARS.  With  Folding 
Plates  and  Diagrams.  By  Sanford  A.  Moss,  M.S  ,  Ph.D  Re- 
printed from  "The  American  Machinist,"  with  revisions  and 
additions.  Second  edition. 

No.  120.  ART  OF  GENERATING  GEAR  TEETH.  By  Howard  A. 
Coombs.  With  Figures,  Diagrams  and  Folding  Plates.  Re- 
printed from  the  "American  Machinist." 

No.  121.  ELEMENTS  OF  GAS  ENGINE  DESIGN.  Reprint  of  a  Set 
of  Notes  accompanying  a  Course  of  Lectures  delivered  at  Cornell 
University  in  1902.  By  Sanford  A.  Moss.  Illustrated. 

No.  122.  SHAFT  GOVERNORS.  By  W.  Trinks  and  C.  Housum.  Il- 
lustrated. 

No.  123.  FURNACE  DRAFT;  ITS  PRODUCTION  BY  MECHANICAL 
Methods.  A  Handy  Reference  Book,  with  figures  and  tables.  By 
William  Wallace  Christie.  Illustrated. 


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27APB51HB 

l9Apr'51lV) 

NOV  27  1992 

LD  21-100m-8,'34 

YC  669 


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